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These NCERT Solutions for Class 6 Science Chapter 9 The Living Organisms and their Surroundings Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

The Living Organisms and their Surroundings NCERT Solutions for Class 6 Science Chapter 9

Class 6 Science Chapter 9 The Living Organisms and their Surroundings Textbook Exercise Questions and Answers

Question 1.
What is a habitat?
Answer:
The surroundings where animals dwell in comfort zone is called a habitat. The animals depend on their habitat for their shelter, food, water and other needs. Example: Lion lives in a forest.

Question 2.
How are cactus adapted to survive in a desert?
Answer:
A cactus is able to survive in a desert as it is adapted to hot and dry condition of the desert. To survive in a desert, the cactus has the following adaptations:

• It has long roots that go deep inside the soil for absorbing water.
• Its leaves are present in the form of spines to prevent water loss through transpiration.
• Its stem is covered with a thick waxy layer to retain water.

Question 3.
Fill up the blanks
a. The presence of specific features which enables a plant or an animal to live in a particular habitat is called ……………….
b. The habitats of the plants and animals that live on land are called ………………. habitats.
c. The habitats of plants and animals that live in water are called ………………. habitats.
d. Soil, water and air are the ………………. factors of habitats.
e. Changes in our surroundings that make us respond to them are called ……………….
Answer:
a. adaptation
b. terrestrial
c. aquatic
d. abiotic
e. stimuli

Question 4.
Which of the things in the following list are non-living?
Plough, Mushrooms, Sewing machine, Radio, Boat, Water hyacinth, Earthworm
Answer:
Plough, Sewing machine, Radio and Boat.

Question 5.
Give an example of a non-living thing which shows any two characteristics of living things.
Answer:
Car is an example of non-living thing which shows characteristics of living things.

• It can move from one place to another.
• It also requires energy just like living things.

Question 6.
Which of the following non-living things were once part of a living thing?
Butter, Leather, Soil, Wool, Electric Bulb, Cooking oil, Salt, Apple, Rubber
Answer:
Butter, leather, wool, cooking oil, apple and rubber were once part of a living thing.

Question 7.
List the common characteristics of the living things.
Answer:
Some common characteristics of the living things are:

• They require food.
• They respire and excrete waste material.
• They respond to stimuli in their environment.
• They reproduce to maintain their number.
• They move from one place to another.
• They grow and die.

Question 8.
Explain why speed is important for survival in grasslands for animals that live there. (Hint: there are few trees or places for animals to hide in grasslands habitats.)
Answer:
In grasslands, mainly grasses are found. Trees are very few in number. Predators such as lions, tigers, etc., that feed upon other animals are commonly found in these regions. It is very easy for these predators to locate their prey in grass.

Therefore, to protect themselves from these predators animals adapt themselves by increasing their speed. The increased speed of the animals help the weaker animals to escape their predator, thereby protecting themselves and increasing the chances for their survival.

NCERT Extended Learning Activities And Projects

Question 1.
Many magazines and newspapers talk about possibility of life outside the Earth. Read these articles and have a discussion in the class about what could be defined as life outside Earth.
Hint:
Do it yourself.

Question 2.
Visit a local zoo and find out what special arrangements are made for the animals that have been brought there from different habitats.
Hint:
Do it yourself.

Question 3.
Find out where are the habitats of the polar bear and the penguin. For each animal, explain two ways in which it is well adapted to its habitat.
Hint:
Both polar bears and penguins are found in polar regions covered with snow. They have thick fur and fatty layer under their skin to protect them from cold. They are also good swimmers as swimming keeps their body warm. They have the body colour that helps them in hiding in the white background of the snow.

Question 4.
Find out which animals live in the foot-hills of the Himalayas. Find out if the types and varieties of animals and plants changes as one goes higher into the mountain regions of the Himalayas.
Hint:
Snow leopards, takins. musk deer, red pandas, tigers, black bear, elephant, shrews, giant panda, golden eagle, alpine, etc., are found in this region. The biodiversity changes with change in altitude.

Question 5.
Make a habitat album. Try to obtain pictures of animals and plants that you have listed in Activity 1 (of NCERT textbook) and paste these under different habitat sections in the album. Draw the leaf shapes and structures for trees found in these different regions and include these in the album. In addition, draw the patterns of branching found in trees of these different regions and include these also in the album.
Hint:
Do it yourself.

Activity 1

Objective: To show the effect of some abiotic factors on the germination of seeds to form young plants.
Material Required: Moong seeds, water.
Procedure:

• Take some moong seeds.
• Keep some dry moong seeds completely submerged in water for a few days.
• Keep them soaked in water for a few days.
• Keep the soaked and wet moong seeds in sunlight for a few days.
• Keep some soaked and wet moong seeds in a completely dark place for a few days.
• Keep some soaked and wet moong seeds in a very cold place, like a refrigerator, for few days.
• Observe them carefully.

Observations: After a few days we will observe that:
i. The dry moong seeds do not germinate at all due to the lack of water and water is essential for the germination of seeds.
ii. The moong seeds submerged in water also do not germinate showing that air is also necessary for the growth of plants.
iii. The wet moong seeds kept in sunlight germinate and grow maximum showing that the sunlight is necessary for the growth of plants.
iv. The wet moong seeds kept in dark place do not grow at all.
v. The wet moong seeds kept in very cold place grow very slow showing that the temperature (heat or warmth is necessary for the growth of plants).

Conclusion: The abiotic factors such as water, air, sunlight and temperature are very important for the growth of plants.

A habitat can be classified into three major types:
i. Terrestrial Habitat: Terrestrial habitat is the habitat for living beings who live on land, for example, humans.
ii. Aquatic Habitat: Aquatic habitat is the habitat for living beings who live in water, for example, fish.
iii Aerial Habitat: Aerial habitat is the habitat for living things who spend most of their life in air, for example, birds.

• Adaptation: Adaptation is the presence of some specific features in the body which help a plant or an animal to live or survive in a particular condition. For example, camel is adapted to live in desert whereas penguin is adapted to live in very cold places near water.
• Xerophytes: Xerophytes are the plants like cactus, agave, etc., which grow in deserts or in very dry places where there is scarcity of water.
• Nocturnal: It is an adaptation in many desert animals who remain inactive during day time and become active during the night to prevent the loss of water from their body.
• Hibernation: Hibernation is the long sleep for eight to nine months in a year. Certain animals hide themselves in burrows with gelatinous secretions and hibernate for long time.

Some major terrestrial habitats are described below:
i. Deserts: These-ere extremely hot and dry habitats with scarcity of water. There are desert animals like rats and snakes, which do not have long legs like a camel has. To stay away from the intense heat during the day, they stay in burrows deep in the sand and come out only during the night, when it is cooler. Desert plants lose very little water through transpiration as the leaves in desert plants are either absent, very small, or they are in the form of spines. Photosynthesis in these plants is usually carried out by the stems. The leaves and stem of desert plants is also covered with a thick waxy layer, which helps to retain Most desert plants have roots that go very deep into the soil for absorbing water.

Activity 2

Objectives: To show that a desert plant such as cactus loses very little water through transpiration.
Materials required: A potted cactus plant and a potted leafy plant.
Procedure:

• Take a potted cactus plant and a potted leafy plant and tie some parts of both the plants with polythene bags separately.
• Keep both the plants in sunlight for few hours.
• Observe both the plants for a few days.

Observations: Only a very small amount of water droplets are present in the polythene bag tied to the cactus plant but more water drops are present in the polythene bag tied to the leafy plant.
Conclusion: Because of the process of transpiration, the cactus plant loses very little water.

ii. Mountains: These habitats are normally very cold and windy. In some areas, snowfall may take place in winters. The trees in such areas are normally cone shaped and have sloping branches with needle-like leaves. This helps the rainwater and snow to slide off easily. Animals living in the mountain regions have thick skin or fur to protect them from cold. For example, yaks have long hair to keep them warm. Snow leopard has thick fur on its body. The mountain goat has strong hooves for running up the rocky slopes of the mountains.

iii. Grasslands: These are the places covered with wide fields of grasses and sometimes forests. Animals like lion and deer are found in grasslands. Lions have long claws in their front legs and is light brown in colour. It helps it to hide in dry grasslands when it hunts for prey. The eyes in front of the face allow it to locate its prey accurately. A deer also lives in grasslands. It has strong teeth for chewing hard plant stems of the forest. It has long ears to hear movements of predators. The eyes on the side of its head allow it to look in all directions for danger. The speed of the deer helps them to run away from the predators.

Some major aquatic habitats are described below:
i. Oceans and seas: These are large water bodies that have saline (salty water). Sea animals have streamlined bodies to help them move easily in water. There are some sea animals, like squids and octopus, which do not have streamlined shape. They stay deeper in the ocean, near the seabed. Sea animals have gills to help them use oxygen dissolved in water. Dolphins and whales breathe in air through nostrils or blowholes that are located n the upper parts of their heads. This allows them to breathe in air when they swim near the surface of water. They can stay inside the water for a long time without breathing.

ii. Ponds and Lakes: These are small freshwater bodies. In aquatic plants, roots are much reduced in size and their main function is to hold the plant in place. The stems of these plants are long, hollow and light. The leaves and flowers, float on the surface of water. Some aquatic plants are completely submerged in water. Some of these plants have narrow and thin ribbon-like leaves. Frogs can stay both inside the water as well as move on land. They have strong back legs that help them in leaping and catching their prey. They have webbed feet which help them swim in water.

Characterises of Living organisms:

• Food: All living organisms, whether plans or animals, eat food to get energy to live.
• Growth: All living beings grow with times. Plants grow from a seed into a big tree.
• Response to stimuli: Changes in the surroundings are called stimuli. Living organisms react to various stimuli.
• Movement: All organisms moves. Humans and animals can move from one place to another. Plants move by bending towards light or curling their leaves as in mimosa plant.
• Respiration: Respiration is the process in which food taken by an organism combines with oxygen to release energy. In this process carbon dioxide is given out.
• Excretion: Excretion is the process of removal of waste substances from the body of living things.
• Reproduction: Reproduction is the process by which living things produce more organisms of their own kind. This process takes place in many different ways, for different organisms.

Activity 3

Objective: To show that living things produce more of their own kind through reproduction.
Materials required: A rose plant.
Procedure:

• Take a cutting from the plant which should have some buds on it.
• Burry its lower part into the soil.
• Observe it for a few days.

Observations: The cutting develops roots and grows into a new plant.
Conclusion: Plants reproduce to give new plants.

Class 6 Science Chapter 9 The Living Organisms and their Surroundings Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Name some biotic components of the environment.
Answer:
Plants, animals, human beings, microorganisms.

Question 2.
Name some abiotic components of environment.
Answer:
Rocks, air, temperature, water, etc.

Question 3.
What things does a habitat provide to the living organisms?
Answer:
Food, shelter, favourable climate and conditions to survive.

Question 4.
List out the different types of habitats.
Answer:

• Terrestrial habitat
• Aquatic habitat

Question 5.
Name a few plants that live in ponds.
Answer:
Hydrilla, lotus, hyacinth, etc.

Question 6.
Which is the most common adaptation found in all animals living in cold places like mountains?
Answer:
They have thick skin or fur to protect themselves from cold environment.

Question 7.
Name two aquatic plants which are completely submerged in water.
Answer:
Lily and lotus.

Question 8.
What is common in all fishes?
Answer:
They have gills, streamlined body, fins and tails.

Question 9.
How does gills help a fish?
Answer:
Gills help to use oxygen dissolved in water.

Question 10.
Name an animal who uses its skin for the process of respiration.
Answer:
Earthworm.

Question 11.
Name some terrestrial habitats.
Answer:
Deserts, mountains, grasslands, forests, etc.

Question 12.
Name some aquatic habitats.
Answer:
Oceans, ponds, lakes, etc.

Question 13.
Define excretion.
Answer:
The process of getting rid of the body waste by the living organisms is known as excretion.

Question 14.
What is reproduction?
Answer:
The process by which living organisms produce more of their own kind is called reproduction.

Question 15.
What are blowholes?
Answer:
The organs by which dolphins or whales breathe in air are called blowholes or nostrils.

Short Answer Type Questions

Question 1.
What is the difference between terrestrial habitat and aquatic habitat? Give examples of each.
Answer:
Terrestrial Habitat:
The habitat of the plants and animals that live on land is called terrestrial habitat. Example, plants like banyan, pine, etc., and animals like elephant, lions, etc., live in the terrestrial habitats.

Aquatic Habitat:
The habitat of plants and animals that live in water is called aquatic habitat. Example, plants like Hydrilla, lotus, etc. and animals like fish and octopus live in aquatic habitats.

Question 2.
Define the term adaptation.
Answer:
The presence of specific features of certain habits which enable a plant or an animal to live in its surroundings is called adaptation.

Question 3.
Describe a desert region.
Answer:
The desert region is very hot in day time and cold at night. A very little amount of water is present in desert. Animals that live in deserts remain inactive during day and become active at night. Camels, lizards, snakes, etc., are some animals that live in desert.

Question 4.
What are the adaptations of fish that make help them to live in water?
Answer:

• The streamlined body of the fish helps in movement in water.
• The slippery scales/skin on the body of fish protect their body.
• They have flat fins and tails which help them to swim, change direction and to keep the body balance.
• Their gills help them to breathe in water.

Question 5.
What features of mountain goats help them to live in cold climate?
Answer:
a. The mountain goats have long hair to protect them from cold and keep warm.
b. The mountain goats have strong hooves for running up the rocky slopes of mountains for grazing.

Question 6.
Why do we need abiotic components?
Answer:
The abiotic components like air, water, light and heat are very important for the growth of plants. These abiotic components are also very important for the growth and the development of animals.

Question 7.
What are the various adaptations of carnivorous animals who live in grasslands?
Answer:

• Sharp and long claws in their front legs to catch, hold and tear the body of their prey.
• Light brown colour or patchy body helps them to hide them in dry grass.
• The eyes in front of the face help in locating their prey.
• Long and strong canines (front teeth) help them in tearing the body of their prey.

Question 8.
Write the important adaptations for aerial animals.
Answer:

• They have hollow bones containing air cavities to make the body light.
• Presence of feathers and wings to fly. The forelimbs are modified into wings for flying.
• Eye sight is very sharp.
• Joints in the bones are completely fused.

Question 9.
Write four main characteristics of living things.
Answer:

• All living things need food to grow and get energy.
• Living things respire to get energy.
• Living things excrete body waste.
• Living things respond to stimuli.

Long Answer Type Questions

Question 1.
What the adaptations of plants who grow in deserts?
Answer:
The plants that grow in deserts show adaptations in their roots, stems and leaves.

• Roots: Their long roots are spread to the deeper layers of the soil so that water can be absorbed.
• Stem: They have spongy stem to store water. The green stem takes over the functions of leaves. Thick waxy coating of the stem develops to prevent the loss of water due to the intense heat.
• Leaves: Their leaves are reduced to spines in order to reduce the loss of water from the surface of leaves.

Question 2.
Write the adaptations in snow leopard which helps it to live in extremely cold places.
Answer:

• The thick fur on the body of snow leopard protects it from cold and keeps it warm. It has fur on its feet and toes too. This protects its feet from cold when it walks on the snow.
• The thick layer of fat beneath its skin for insulation protects it from cold.
• Snow leopard has a rounded body and small ears to keep the body surface area to a minimum. This reduces the heat loss from the body of snow leopard.
• The snow leopard has big feet to spread the weight on snow and prevent it from sinking into the soiled snow.

Question 3.
How is a deer is adapted to forest habitat? Explain.
Answer:

• The deer has eyes on the sides of its head which enable it to see in all directions at the same time. The all round vision of deer helps it to see animals like lion, in all the area around it.
• The deer has big ears for good hearing. The big ears help the deer to hear the movements of predators like lion very easily.
• The deer is fast and agile animal. The speed of deer helps it to run away from the predators like lion which try to catch it.
• The deer has brown colour which helps it to hide in dry grasslands without being noticed by lion, etc.
• The deer has strong teeth for chewing hard plant stems of the forest.

Picture-Based Questions

Question 1.
a. Identify the habits A and B.

b. Given an example of an animal found in each of these habitats.
c. Write one adaptation of plants found in each of these regions.
Answer:
a. A – Desert; B – Mountain
b. Lizard is found in desert and snow leopard on mountains.
c. Desert plants have leaves reduced to spines.
Plants in mountains have needle like leaves.

Question 2.
a. Identify the living organism shown below.

b. What is its habitat?
c. Write one adaptive feature of this organism.
Answer:
a. Bird.
b. Aerial habitat.
c. Its forelimbs are modified into wings that help it in flying.

These NCERT Solutions for Class 6 Science Chapter 10 Motion and Measurement of Distances Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Motion and Measurement of Distances NCERT Solutions for Class 6 Science Chapter 10

Class 6 Science Chapter 10 Motion and Measurement of Distances Textbook Exercise Questions and Answers

Question 1.
Give two examples each of modes of transport used on land, water and air.
Answer:
Mode of transport on land: Buses, railways
Mode of transport in water: Boats, ships Modes of transport in air: Airplanes, gas balloons.

Question 2.
Fill in the blanks:
a. One metre is ……………… cm.
b. Five kilometre is ……………… m.
c. Motion of a child on a swing is ………………
d. Motion of the needle of a sewing machine is ………………
e. Motion of wheel of a bicycle is ………………
Answer:
a. 100
b. 5000
c. oscillatory motion
d. periodic motion
e. circular motion

Question 3.
Why can a pace or a footstep not be used as a standard unit of length?
Answer:
The pace or a footstep has different lengths for different persons. So they cannot be used as a standard unit of length.

Question 4.
Arrange the following lengths in their increasing magnitude:
1 metre, 1 centimetre, 1 kilometre, 1 millimetre.
Answer:
1 millimetre > 1 centimetre > 1 metre > 1 kilometre

Question 5.
The height of a person is 1,65 m. Express it into cm and mm.
Answer:
a. 165 cm, as one metre = 100 cm
= 1.65 × 100 cm = 165 cm
b. 1.65 × 100 × 10 mm = 1650 mm

Question 6.
The distance between Radha’s home and her school is 3250 m. Express this distance into km.
Answer:
As one km = 1000 m
So, 3250 m = 3250/1000 km = 3.250 km

Question 7.
While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm and at the other end is 33.1 cm. What is the length of the needle?
Answer:
Length of needle = 33.1 cm – 3.0 cm = 30.1 cm.

Question 8.
Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Answer:
The motion of a bicycle and a ceiling fan are in circular motion. Thus both show similar motion. But the ceiling fan moves without changing its position while the bicycle moves with changing its position with time. This shows dissimilarities between two motions.

Question 9.
Why would you not like to use a measuring tape made of an elastic material like rubber to measure distance? What would be some of the problems you would meet in telling someone about a distance you measured with such a tape?
Answer:
Elastic material will not give accurate measurement because its stretches in length and reduces in size when not stretched. While telling the measurement taken with an elastic tape, we have to tell whether the tape was stretched and by how much, which is very difficult.

Question 10.
Give two examples of periodic motion.
Answer:
The motion of pendulum of clock and the motion of child on a swing are the two examples of periodic motion.

NCERT Extended Learning Activities And Projects

Question 1.
Draw a map of your classroom. Roll a ball on the floor. In your map mark the points where the ball started and where it stopped. Show’ also the path it moved along. Did the ball move along a straight line?
Hint: The ball will move in a straight line unless a force is applied on it.

Question 2.
Using string and a scale, let each student measure the length of his/her foot. Prepare a bar graph of the foot length measurements that have been obtained for the whole class.
Hint: Do it yourself.

Activity 1

Objective: To measure the length of a table using hand span.
Materials Required: A table.
Procedure:

• Stretch your hand for measuring the length of the table.
• Move it along the length of the table.
• Count the number of hand spans you move along the length.
• Repeat the process thrice.

Observations: The number of hand spans is …………… each time.
Conclusion: The length of the table is …………… hand spans.

Measurement of Length: The SI unit of length is metre (m). While measuring length, following points should be kept in mind:
i. The scale should be placed along the length of object.
ii. The scale should be placed exactly in a straight line.
iii. Reading should be taken from the zero mark of the scale and not from its edge.

Activity 2

Objective: To measure the length of a curved line using a thread.
Materials Required: A thread.
Procedure:

• Draw a curved line on a sheet of paper.
• Place the paper on a smooth surface.
• Mark the beginning point of the line as point A and end point as point B.
• Take the thread and place it along the line keeping it touch with the help of your thumb or forefinger.
• Put the thread on the line from point A to point B.
• Now, stretch the thread along a metre scale and measure the length between the two marks.

Conclusion: The length of the curved line is ………………. cm.

Rest: Rest is when a body does not change its position over time.
Motion: Motion is when an object changes its position over time. There are various types of motion:
i. Linear Motion: Linear motion is the motion when a body moves along a straight line path. Eg., a car moving on straight road.
ii. Circular Motion: Circular motion is the motion when a body moves along a circular path. Eg., motion of the hands of a clock.

iii. Rotational Motion: Rotational motion is the motion when an object turns about a fixed axis. Eg., rotation of a top and the earth.
iv. Periodic Motion: Periodic motion is the motion which repeats itself after regular intervals of time. Eg, motion of a pendulum.

Activity 3

Objective: To classify the following objects at rest or in motion.
House, table, clock, a school bag, a stone lying on the ground, a flying bird, second’s hand of the clock, a moving train, a child on the swing, heart beat in a healthy person and a spin ball in cricket.
Observations :

• Objects at rest: House, table, clock, a school bag, a stone lying on the ground.
• Objects in motion: Flying bird, second’s hand of clock, moving train, child on a swing, heartbeat in a healthy person, spin ball in cricket.

Conclusion:

• The objects at rest do not change their position with respect to time.
• The objects in motion change their position with the time.

Class 6 Science Chapter 10 Motion and Measurement of Distances Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
In prehistoric times, which animals were used as means transport?
Answer:
Horses, camels, oxen.

Question 2.
Name two water transports and two air transports.
Answer:
Boats and ships are the means of water transport. Airplanes and hot air balloons are the means of air transport.

Question 3.
What is cubit?
Answer:
Cubit is a unit of measurement which includes the distance from elbow to the tip of the middle finger.

Question 4.
What is the standard unit of measuring length?
Answer:
Metre is the standard unit of measuring length.

Question 5.
What is the use of a ruler?
Answer:
Ruler is used to measure lengths of straight objects.

Question 6.
When is an object said to be in rest?
Answer:
When an object does not change its position with respect to time and the observer the object is said to be in rest.

Question 7.
When is an object said to be in motion?
Answer:
When the object changes its position with respect to time and the observer, the object is said to be in motion.

Question 8.
Which motion takes place in fixed direction?
Answer:
Linear motion.

Question 9.
Define periodic motion.
Answer:
The motion which repeats itself after regular intervals of time is called periodic motion.

Question 10.
Name the types of motion which a body undergoes during rolling.
Answer:
Translatory and rotatory motion.

Question 11.
Why do people need transport?
Answer:
To move from one place to another.

Question 12.
Which invention made a great change in the modes of transport?
Answer:
Invention of wheel.

Question 13.
Were one cubit or one pace accurate unit of measurement?
Answer:
No.

Question 14.
Which measuring device is required to measure the chest of a person?
Answer:
Measuring tape.

Question 15.
Which type of motion can be seen in the ball rolling on ground?
Answer:
Linear motion.

Short Answer Type Questions

Question 1.
Which units of measurement were derived from the length of some parts of human body?
Answer:
A pace or a footstep, a cubit that is the distance from the elbow to the tip of the middle finger, hand span and width of the fingers.

Question 2.
Define standard unit of measurement.
Answer:
A unit of measurement which has a fixed value and does not change from person to person or place to place is called a standard unit of measurement.

Question 3.
Which precautions should be taken while measuring the length with a metre scale?
Answer:

• The initial point of distance must coincide with the zero reading of metre scale.
• The eye should be kept in line with the point of measurement.
• The scale should be perfectly horizontal.

Question 4.
What is rotational motion? Give two examples of rotational motion.
Answer:
When an object turns about a fixed axis, it is called rotational motion. A spinning top and rotation of the earth on its axis are the examples of rotational motion.

Question 5.
Which types of motion are shown by a bicycle?
Answer:
Suppose a bicycle is moving on a straight road. The wheel of bicycle is rotating on its axis and also moving forward in a straight line path. So, a bicycle on a straight road has two types of motion: rotational motion as well as rectilinear motion.

Question 6.
Give a method to measure the thickness of one rupee coin.
Answer:
Collect ten one rupee coins and stack them. Measure the height of the stacked coins in millimetres. Tick the thickness of ten coins. Divide this thickness by 10. You will get the average thickness of one coin.

Question 7.
How does merry-go-round show two types of motion?
Answer:
Merry go round as a whole shows rotatory motion as it turns on its own axle. But the outer part of merry go round on which the children sit shows circular motion. Thus, the child sitting on a merry go round will exhibit circular motion.

Question 8.
How can a measured length be expressed?
Answer:
A measured length can be expressed by

• a number describing the numerical value.
• the unit in which that quantity is measured.

Question 9.
What are the advantages of using a measuring scale?
Answer:

• The scale can be easily taken from one place to another,
• The scale does not change during measurements.

Long Answer Type Questions

Question 1.
What is the standard unit of measurement? Why is it required?
Answer:
A unit of measurement which has a fixed value and which does not change from person to person or place to place, is called a standard unit of measurement. It is required to make our judgments more reliable and accurate. For proper dealing, measurement should be same for everybody. Thus, there should be uniformity in measurement. For the sake of uniformity we need a common set of units of measurements.

Question 2.
What is the proper way of using a measuring scale?
Answer:
a. The scale should be placed along the length to be measured. The scale should be placed very close to the object to be measured.

b. Keep your eye in line with the point of measurement. If the eye is not in line with the point of measurement, the measured length will be either shorter or longer than the actual length.

c. Do not start measurement from the worn out or damaged end of the scale. If the zero end of the scale is damaged, start measurement from some other mark of the scale. Then the actual length of the object is equal to the difference between the readings at the two points.

Question 3.
Define motion. Explain the different types of motion.
Answer:
When an object changes its position with respect to time and observer, it is said to be in motion. The different types of motion are:
a. Rectilinear motion: When a body moves along a straight line, it is called rectilinear motion. Motion of train on straight track and motion of a falling stone are the examples of rectilinear motion.

b. Circular motion: When a body moves along a circular path, it is called circular motion. Movement of the earth around the sun and movement of the moon around the earth the examples of circular motion.

c. Rotational motion: When an object turns about a fixed axis, it is called rotational motion. Spinning of top and spinning of the earth on its axis are the examples of rotational motion.

d. Periodic motion: The motion which repeats itself after regular intervals of time, is called periodic motion. Motion of second’s hand of clock and the revolutions of earth around the sun are the examples of periodic motion.

Picture-Based Questions

Question 1.
a. Identify the device shown below.

b. What type of motion does it exhibit?
c. Give one more example of such motion.
Answer:
a. Pendulum
b. Periodic motion
c. Motion of a child on a swing is periodic.

Question 2.
a. Identify the devices A and B.

b. What are they used for?
c. What is the SI unit of the quantity measured by these devices?
Answer:
a. A – Measuring scale.
B – Measuring tape.
b. They are used to measure length of objects.
c. Metre (m).

These NCERT Solutions for Class 6 Science Chapter 8 Body Movement Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Body Movement NCERT Solutions for Class 6 Science Chapter 8

Class 6 Science Chapter 8 Body Movement Textbook Exercise Questions and Answers

Question 1.
Fill in the blanks:
a. Joints of the bones help in the ……………. of the body.
b. A combination of bones and cartilage from the ……………. of the body.
c. The bones at the elbow are joined by a ……………. joint.
d. The contraction of the ……………. pulls the bones during movement.
Answer:
a. movement
b. skeletal
c. ball
d. muscles

Question 2.
Indicate true (T) and false (F) among the following sentences.
a. The movement and locomotion of all animals is exactly the same.
b. The cartilages are harder than bones.
c. The finger bones do not have joints.
d. The forearm has two bones.
e. Cockroaches have an outer skeleton.
Answer:
a. False
b. False
c. True
d. True
e. True

Question 3.
Match the items in Column I with one or more items of Column II.

Answer:
1. (d),
2. (a),
3. (e),
4. (f),
5. (b).

Question 4.
Answer the following questions.
a. What is a ball and socket joint?
b. Which of the skull bones are movable?
c. Why can our elbow not move backwards?
Answer:
a. The rounded end of bone fits into the cavity of the other bone. Such a joint allows movements in all directions. This type of joint is called ball and socket joint.
b. The facial bones of our skull comprise upper and lower jaw, in which lower jaw is movable.
c. Our elbow has hinge joint. These joints allow movement only in one plane like a door hinge and not more than 180 degrees.

Activity 1

Objective: To show that we are able to bend or rotate our body only at joints.
Materials Required: Wooden scale arid ropes threads.
Procedure:

• Straighten your right arm.
• Ask your teacher or friend to tie a wooden scale lengthwise under the arm in such a way that the elbow is in the centre.

Now, try to bend the arm.
Observations: After tying the scale, we cannot bend the arm at the elbow.
Conclusion: We can see that we can bend or move our body at joints only.

i. Fixed Joints: Fixed joints are the joints where two bones are held so tightly together by strong fibres that they cannot move at all. Fixed joints occur in our skull.
ii. Synovial Joints: Synovial joints are freely movable joints which allow free movements in one or more directions. Following are some synovial joints:

a. Ball and Socket Joint: Ball and socket joint allows movement of the bones in all the directions. Hip joint and shoulder joint have ball and socket joint.

Activity 2

Objective: To make a ball and socket joint.
Materials Required: A strip of paper, a rubber or plastic ball.
Procedure:

• Roll the paper strip into cylindrical shape.
• Make a hole in ball and push the paper cylinder into it.
• Put the ball in a small bowl. The ball and socket joint is ready.

Observation: This formation allowed free movement of the paper in the ball.
Conclusion: The rounded end of one bone fits into the cavity of the other bone is called the ball and socket joint.

b. Pivotal Joint: Pivotal joint allows movement in many planes. Skull makes such joint with the first two vertebrae.
c. Hinge Joint: Hinge joint allows movement only in one direction. Fingers have this type of joint.
d. Gliding Joint: Gliding joint allows a limited movement due to sliding nature of cartilages. Movable joints of the backbone are gliding joints.

Skeletal System: Skeletal system is the framework of bones and cartilages which supports the body. It consists of the following parts:
i. Skull: Skull is the bony part of head which is made of 22 bony plates joined together.

ii. Backbone: Backbone is a long hollow, rod like structure running from the neck to the hips inside the body.
Vertebrae are the small bones which make up the backbone.
iii. Ribcage: Ribcage is 12 pairs of ribs along with backbone making a cone-shaped cage which protects the lungs and the heart.

Activity 3

Objective: To feel the chest bones and the backbone.
Procedure:

• Take a deep breath and hold it for a little while. Feel your chest bones and the backbone by gently pressing the middle of the chest and back at the same time.
• Count as many ribs (bones of the chest) as possible.
• Observe the given figure carefully and compare with what you feel of the chest bones.
• We see that the ribs are curiously bent.
• Ask a friend to touch his toes without bending his knees.
• Put your fingers at the centre of his back. Feel some long and hard structure.
• Starting from the neck, move your fingers downwards on the back of your friend.

Observation: Rib join the chest bone and the backbone together to form a box. This is called the rib cage. Some important internal parts of our body lie protected inside this cage.
Conclusion: Backbone is made of many small bones. The rib cage is joined to these bones.

iv. Carpels: These are the several small bones forming the wrist.
v. Tarsals: These are the several small bones forming the ankle.
vi. Pectoral bones: These are the bones forming the shoulder join.
vii. Pelvic bones: These are the bones forming the hip joint.

Muscles can be classified into two types: i. Voluntary muscles: These are the muscles that can be moved with your own will. For example, you can move your hand up and down with your own will as it has voluntary muscles.
ii. Involuntary muscles: These are the muscles that cannot be moved by your will. For example, you cannot move the muscles of your ear pinna or the muscles of your scalp by your will.

Cartilage: Cartilage is a solid but semi-rigid and flexible tissue which smoothens bones surfaces at joints. It also helps in forming the framework of the body called skeleton. Nose, ear, trachea and larynx have cartilage.

Gait of Animals
i. Earthworm: The body of an earthworm is made up of many rings joined end to end. It lacks bones. It has muscles which help to extend and shorten the body. During movement, it first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases the rear end. It then shortens the body and pulls the rear end forward. In this way, the earthworm can move through soil. Its body secretes a slimy substance to help the movement.

ii. Snail: It has a shell which is the outer skeleton of the snail, but is not made of bones. A thick structure, called foot, and the head of the snail may come out of an opening in the shell. The foot is made of strong muscles. The wavy motion of the foot can be seen in a snail.

iii. Cockroach: Cockroaches walk, climb as well as fly in the air. They have three pairs of legs that help in walking. Their body is covered with a hard, outer skeleton is made of number of plates joined together that permit movement. There are two pairs of wings attached to the body that help in flying.

iv. Birds: Birds fly in the air and walk on the ground. Some birds such as ducks and swans can also swim in water. Their bones are hollow and light. The bones of the hind limbs are used for walking and perching. The forelimbs are modified as wings. The shoulder bones are strong. The breastbones are modified to hold muscles of flight which are used to move the wings up and down.

v. Fish: The head and tail of the fish are smaller than the middle portion of the body. This body shape is called streamlined. This shape allow the fish to move in water. The skeleton of the fish is covered with strong muscles. The fish forms a curve while swimming. Then, quickly, the body and tail curve to the other side. This makes a jerk and pushes the body forward. This is helped by the fins of the tail. Fish also have other fins on their body which mainly help to keep the balance of the body and to keep direction while swimming.

vi. Snake: Snakes have a long backbone and many thin muscles. Muscles also interconnect the backbone, ribs and skin. The snake’s body curves into many loops, each loop giving it a forward push by pressing against the ground. The snake moves forward very fast and not in a straight line. It is called slithering movement.

Class 6 Science Chapter 8 Body Movement Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Name two types of joints.
Answer:
Fixed joints and movable joints

Question 2.
Name four movable joints.
Answer:
a. Ball and socket joint
b. Pivotal joint
c. Hinge joint
d. Gliding joint

Question 3.
Give two examples of hinge joint.
Answer:
Elbow joint and knee joint.

Question 4.
Name the two main parts of skull.
Answer:
Cranium and facial bones.

Question 5.
What is backbone made of?
Answer:
The backbone is made up of small bones known as vertebrae.

Question 6.
Which internal organs are protected by rib cage?
Answer:
Heart, lungs and liver.

Question 7.
What is patella?
Answer:
Knee cap is called patella.

Question 8.
Which two types of muscles does an earthworm’s body have?
Answer:
Circular muscles and longitudinal muscles.

Question 9.
What is slithering?
Answer:
The movement of snake is called slithering.

Question 10.
Name an animal which swims in water by moving its tail from side to side.
Answer:
Fish.

Short Answer Type Questions

Question 1.
Where are these joints located in your body?
a. Ball and socket joint
b. Pivotal joint
c. Hinge joint
d. Gliding joint.
Answer:
a. Between shoulder and upper arm; between thigh and hip
b. Between the first vertebrae and axis vertebrae
c. Knee joint
d. Movable joints of backbone

Question 2.
What is a cartilage? Where is it present?
Answer:
A solid but semi-rigid and flexible tissue is called cartilage. It smoothens bone surfaces at joints. It is present in the nose tip, ear pinna, trachea and larynx.

Question 3.
Define endoskeleton with example.
Answer:
The skeleton which lies inside the body and is covered by soft parts like flesh is known as endoskeleton. Example, humans, elephants, dogs, etc., have endoskeleton.

Question 4.
Define tendons and ligaments.
Answer:
The bones are connected to muscles with the help of the connective tissues called tendons.
The bones are connected to each other at the joints with tissues called ligaments.

Question 5.
Differentiate between bones and cartilage.
Answer:

Question 6.
What are the main functions of the skull?
Answer:

• Skull protects the brain.
• Skull protects the sense organs of the face like eyes, ears and nose.
• Skull gives shape to our head.

Question 7.
How do muscles work?
Answer:
The muscles work in pairs. When one of them contracts, the bone is pulled in that direction. The other muscle of the pair relaxes. To move the bone in the opposite direction, the relaxed muscle contracts to pull the bone towards its original position while the first one relaxes.

Question 8.
How is the brain protected?
Answer:
The brain is located inside the skull of our body. The brain is protected by cranium, a bony box of the skull. Inside the cranium, the brain is contained in a fluid-filled balloon which provides further shock absorption for protection.

Question 9.
Describe the movements of:
(a) earthworm, (b) snail.
Answer:
a. Earthworm has muscles but no bones.
During the movement, earthworm first extends the front part of the body keeping the rear portion fixed to the ground. Then it fixes the front and releases the rear end. It then shortens the body and pulls the rear end forward. In this way, by repeating such muscular expansions and contractions, earthworm moves.

b. A snail moves with the help of a large, disc-shaped muscular foot. It has two sets of muscles in the foot. These muscles contract and expand alternately producing a kind of wave effect (from back to front). A series of waves in the muscles of the foot make the snail move forward.

Question 10.
How do fish move in water?
Answer:
The body of the fish is streamlined. The streamlined shape helps the fish to move in water. The skeleton of the fish is covered with muscles which make the front part of the body to curve to one side and the tail part swings towards the opposite side. This makes a jerk and pushes the body forward. In this way, it moves in the water.

Long Answer Type Questions

Question 1.
What is backbone? Describe its formation. Write its main functions.
Answer:
The backbone is a long, hollow structure running from the neck to the hips, inside our body. The small bones which make up the backbone are called vertebrae. It consists of 33 small ring-like vertebrae joined end to end. The first 24 vertebrae are joined serially by elastic cartilages. The main nerve cord passes through the hollow tube formed by the vertebrae. The 5 vertebrae of the hip are fuse and inseparable. 4 vertebrae of the tail are also fused.

Main functions of the backbone are:

• It provides main support to the body.
• It supports the head at its top.
• It attaches shoulder bones, ribs and hip bones.
• It protects the spinal cord.

Question 2.
Explain the various kinds of joints found in our body and give an example of each.
Answer:
a. Fixed joints: Those joints which do not allow movement are called fixed joints. Example: Skull bones.

b. Bali and socket joint: In this joint, one end of the bone has a round shape like a ball which fits into a socket in the other bone. It permits movements of the bones in all directions. Example, shoulder joints and hip joints have ball and socket joints.

c. Pivotal joints: Pivotal joint allows rotation only. It occurs between the first vertebrae and axis vertebrae.

d. Hinge joint: This joint allows movement only in one direction, forwards and backwards. Elbow joint and knee joint have this type of joint.

e. Gliding joint: This joint allow a limited movement due to sliding nature of cartilages. Movable joints of backbone are gliding joint.

Question 3.
What is a skeletal system? Write the functions of the skeletal system.
Answer:
The framework of bones and cartilages which supports the body of an animal or human is called the skeletal system.

The main functions of the skeletal system are:

• It holds the whole body together and gives it a shape.
• It protects the delicate internal organs like brain, kidney, heart, lungs, etc.
• It provides numerous points for the attachment of muscles of the body.
• Along with muscles, skeleton helps in the movement of body parts and in locomotion.

Question 4.
Why do animals need locomotion?
Answer:

• Animals move from place to place in search of food.
• It enables the animals to migrate from an unfavourable place or environment to a favourable place or environment.
• It helps the animals to escape from their enemies and predators.
• It helps animals to find their partners for reproduction, and to move to favourable areas for egg laying or rearing of young ones.

Question 5.
Describe the hip bone. Write its main functions.
Answer:
The hip bone forms a large basin shaped frame at the lower end of the backbone to which the legs are attached. The hip bone is also called pelvis. The hip bone encloses the position of our body below the stomach. The thigh bones of our legs are joined to the hip bone by the ball and socket joints.

The main functions of hip bone are:

• Hip bone supports and protects the lower organs of the body such as intestines, urinary bladder and internal sex organs.
• It attaches the legs to our body.
• It provides sides for the attachment of muscles that move legs, hips and trunk.

Question 6.
Explain the structure of leg.
Answer:
The leg includes the thigh, lower leg, ankle, foot and the toes.

• The thigh bone called femur, is the longest and strongest bone in the body.
• The lower leg consists of tw o bones: tibia and fibula.
• The ankle consists of several small bones.
• In the front part of the knee, there is a disc-like knee cap called patella.
• The foot has five longer bones called metatarsals.
• Each toe has three smaller bones.

The toe bones also help us in walking and running. They are called tarsals.

Picture-Based Questions

Question 1.
a. Identify the figure shown here:

b. What type of joint is present between these bones?
c. Give one function of this structure.
Answer:
a. Backbone
b. Gliding joint
c. It protects the spinal cord

Question 2.
a. Identify the figure shown below:

b. Name the type of joint in part marked A.
c. Is the joint marked B movable or not?
Answer:
a. Skull
b. Fixed joint
c. It is immovable.

These NCERT Solutions for Class 6 Science Chapter 7 Getting to Know Plants Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Getting to Know Plants NCERT Solutions for Class 6 Science Chapter 7

Class 6 Science Chapter 7 Getting to Know Plants Textbook Exercise Questions and Answers

Question 1.
Correct the following statements and rewrite them in your notebook.
a. Stem absorbs water and minerals from the soil.
b. Leaves hold the plant upright.
c. Roots conduct water to the leaves.
d. The number of petals and stamens in a flower is always equal.
e. If the sepals of a flower are joined together, its petals are also joined together.
f. If the petals of a flower are joined together, then the pistil is joined to the petal.
Answer:
a. Roots absorb water and minerals from the soil.
b. Stem holds the plant upright.
c. Stem conducts water to the leaves.
d. The number of petals and stamens in a flower may or may not be equal.
e. If the sepals of a flower are joined together, it is not necessary that petals are also joined together.
f. If the petals of a flower are joined together, then it is not necessary that the pistil is joined to the petal.

Question 2.
Draw (a) a leaf, (b) a taproot and (c) a flower.
Answer:

Question 3.
Can you find a plant in your house or in your neighbourhood, which has a long but weak stem? Write its name. In which category will you place it?
Answer:
It is a money plant. It is a climber.

Question 4.
What is the function of a stem?
Answer:
A stem performs following functions:

• Stem transfers water and minerals from roots to various parts of the plant.
• It transports food from leaves to various parts.
• It bears leaves, flowers and fruits,
• It holds the plant upright.

Question 5.
Which of the following leaves have reticulate venation?
Wheat, China rose, maize, tulsi, grass, coriander (dhania).
Answer:
Tulsi, Coriander and China rose have reticulate venation.

Question 6.
If a plant has fibrous root, what type of venation do its leaves have?
Answer:
Parallel venation.

Question 7.
If a plant has leaves with reticulate venation, what kind of roots will it have?
Answer:
Taproot.

Question 8.
Is it possible for you to find out whether a plant has taproot or fibrous roots by looking at the impression of its leaf on a sheet of paper?
Answer:
Yes, if leaf impression shows reticulate venation, the plant is likely to have taproot. However, if the leaf impression shows parallel venation, the plant is likely to have fibrous root.

Question 9.
What are the parts of a flower?
Answer:
The names of various parts of a flower from outside to inside are:

• Sepals
• Petals
• Stamens
• Pistil

Question 10.
From the following plants, which of them have flowers?
Grass, maize, wheat, chilli, tomato, tulsi, peepal, shisham, banyan, mango, jamun, guava, pomegranate, papaya, banana, lemon, sugarcane, potato, groundnut
Answer:
All the above plants have flowers.

Question 11.
Name the part of plant which produces food. Name the process.
Answer:
Leaves produces food and the process is called photosynthesis.

Question 12.
In which part of a flower, you will find the ovary?
Answer:
The ovary is found in pistil part of a flower.

Question 13.
Name two plants in which one has joined sepals and the other has separate sepals.
Answer:
Plants with joined sepals:

1. Dhatura
2. Loki

Plants with separate sepals:

1. China rose
2. Mustard

NCERT Extended Learning Activities And Projects

Question 1.
Become a leaf expert: Do this activity with a number of leaves over a period of few weeks. For every leaf that you wish to study, pluck it and wrap it in a wet cloth and take it home. Now, place the leaf between the folds of a newspaper and place a heavy book on it. You can also put it under your mattress or a trunk! Take out the leaf after a week. Paste it on a paper and write a poem or story about it. With your leaf collection pasted in a book, you can become an expert about leaves!
Answer:
Do it yourself.

Question 2.
Names of plant parts are hidden in this grid. Search them by going up, down, diagonally, forward or backward. Have fun!

Answer:

Activity 1

Objective: To show that water travels up through the stem of a plant.
Materials Required: Two glasses, red ink, freshly cut branches of a plant preferably bearing white flowers and blade.
Procedure:

• Take two glasses with little water in them. Label these glasses as A and B.
• Cut the lower end of the branches obliquely (or at an angle) with the help of a blade.
• Put one branch in each of the glasses. Add a few drops of red-ink into the water in glass A and shake it to mix the ink.

Leave the set up as such overnight. Observe the branches from inside and the flowers if the branches had flowers.
Observations: The branch from inside and the flower on it in glass A appears red. The colour of the branch and the flower in glass B remains unchanged.
Conclusion: Water travels up the stem through narrow tubes in it.

Leaf: It is the green part of the plant that prepares food. A leaf has following parts:
i. Lamina: Lamina is the broad, green part of the leaf.
ii. Petiole: Petiole is the thin stalk with which leaf is attached to the stem or branch.
iii. Midrib: It is the prominent line in the middle of the leaf blade.
iv. Veins: The various small, lateral lines arising from midrib and spread in lamina are called veins.

Venation: Venation is the arrangement of veins in the lamina. All the leaves contain veins. The arrangement of veins in the leaves of various plants is different. It can be of two types:
i. Reticulate venation: If veins make a net-like design on both sides of midrib, it is called reticulate venation. E.g., mango leaf, peepal leaf, etc.
ii. Parallel venation: If the veins are arranged parallel to each other and to the midrib, it is called parallel venation. E.g., grasses.

• Transpiration: Transpiration is the process by which water comes out from the leaves in the form of vapour. It helps the plant in cooling and absorbing nutrients from the root.

Activity 2

Objective: To show transpiration in plants. Materials Required: A potted plant, polythene bag and cello-tape.
Procedure:

• Take a well-watered potted plant having big leaves.

• Enclose a leafy stem (or branch) of the plant in a clean polythene bag and seal the mouth of polythene bag properly with cello-tape.
• Keep this potted plant in the sunshine for 2 to 3 hours.

Observations: A number of water droplets are seen on the inner side of the polythene bag.
Conclusion: The leaves of a plant lose water through transpiration.

• Photosynthesis: Photosynthesis is the process by which green leaves of plants prepare their food in the presence of sunlight, air, water and chlorophyll (a green coloured pigment present in the leaves).

Activity 3

Objective: To show that the leaf has starch in it.
Materials Required: A leaf, spirit, a beaker, test tube, burner, water, a plate and iodine solution.
Procedure:

• Boil a healthy leaf in water for about 10 minutes.
• Put the leaf in a test tube and pour spirit to completely cover the leaf.
• Now, put the test tube in a beaker half filled with water.

• Heat the beaker till all the green colour from the leaf comes out into the spirit in the test tube.
• Take out the leaf carefully and wash it in water.
• Put it on a plate and pour some iodine solution over it.

Observations: The leaf turns blue-black.
Conclusion: The blue-black colour indicates the presence of starch in leaves.

Root: It is the underground part of the plant that anchors it into the ground. Roots absorb water and minerals from the soil and conduct them to the upper parts of plant. Roots can be of two types:
i. Tap root: Tap root is the main root from which many branching roots grow sideways. Pea, radish, carrot, balsam, etc., are some plants that have tap root.
ii. Fibrous root: Fibrous root is the cluster of thin fibre-like roots at the base of the stem. Fibrous root is spread out in the soil. Wheat, maize, grass, etc., have fibrous root.

Flower: It is reproductive part of a plant. A flower consists of the following parts:
i. Sepals: Sepals are the small, green-coloured leaf-like structures seen in the flowers.
ii. Petals: Petals are the big, coloured leaf¬like structures seen in the flowers.
iii. Stamens: Stamens are the long filaments bearing anthers on their tip. They are seen in the flower on the removal of sepals and petals. These are the male parts of a flowers.
iv. Pistil: Pistil is the innermost part of a flower which we cannot see completely. It is the female part of the flower. It comprises of the following structures:
a. Style: Style is the narrow upper portion of pistil.
b. Stigma: Stigma is the sticky end at the top of the style.
c. Ovary: It is the lowermost bulged part of the pistil. It contains ovules that carry egg cells.
On maturation, ovary develops into fruit and ovules develop into seeds.

Very Short Answer Type Questions

Question 1.
What are the plants having green and tender stems called?
Answer:
Herbs.

Question 2.
What type of plant is the grape?
Answer:
Climber.

Question 3.
What is the food making process in green plants called?
Answer:
Photosynthesis.

Question 4.
Name the major parts of a plant.
Answer:
Stem, root, leaves and flowers.

Question 5.
Give two examples of shrubs.
Answer:
Lemon and orange.

Question 6.
Give two examples of trees.
Answer:
Banyan and apple.

Question 7.
Define nodes.
Answer:
The points on the stem where leaves and branches arise are called nodes.

Question 8.
What is lamina?
Answer:
The broad, green, flat part of leaf is called lamina.

Question 9.
What are the two main types of venation in the leaves?
Answer:
a. Reticulate venation
b. Parallel venation.

Question 10.
What are the two types of roots?
Answer:
a. Tap root
b. Fibrous root.

Question 11.
What do you mean by petals?
Answer:
The leaf-like coloured parts next to the sepals are called petals.

Question 12.
What is filament?
Answer:
Each stamen consists of a thin green stalk called filament.

Question 13.
Define ovary.
Answer:
The lower broad or bulged portion of the pistil is called ovary.

Question 14.
Name the agents of pollination.
Answer:
Insects, wind and water.

Question 15.
Name the various parts of stamen.
Answer:
Anther and filament.

Short Answer Type Questions

Question 1.
What are nodes and internodes in stem?
Answer:
Nodes are the points on the stem from where leaves and branches arise and internodes are the spaces between two adjacent nodes.

Question 2.
What is tuber in potato?
Answer:
Potato plant has special stem that grows underground- and stores food for the plant. This special stem is called tuber.

Question 3.
Write the functions of a leaf.
Answer:

• The leaves prepare food for the plant by the process of photosynthesis.
• The leaves get rid of excess water from the plant through transpiration.
• The leaves carry out the process of respiration in plants.

Question 4.
Define venation of the leaf.
Answer:
All the leaves contain veins. The arrangement of veins in the lamina of the leaf is known as venation of the leaf.

Question 5.
How does a climber differ from a creeper?
Answer:
Climber plant has a special organ called tendril on its stem which helps it to climb and grow while creeper has no such organ, so they grow on ground only.

Question 6.
Differentiate between the flowering plants and non-flowering plants.
Answer:
Flowering Plants:
The plants which have roots, stem and leaves, flower and fruits are known as flowering plants.
Examples: mango, guava, grapes, papaya, etc.

Non-flowering Plants:
The plants which do not have definite roots, stem, leaves and flowers are known as non-flowering plants.
Examples: fern, moss, algae, etc.

Question 7.
Write any two functions of roots.
Answer:

1. Roots help in holding the plant firmly in the soil.
2. Roots help in absorption of water and minerals from the soil.

Question 8.
How are leaf venation and type of roots in a plant related?
Answer:
Plants having the reticulate venation have tap roots while plants having the leaves with parallel venation have fibrous roots.

Question 9.
Which are the two gases involved in photosynthesis? How?
Answer:
Carbon dioxide and oxygen are involved in photosynthesis. Carbon dioxide is used whereas oxygen is released in photosynthesis.

Question 10.
What types of plants are called trees?
Answer:
Plants which are tall and have hard, thick brown woody stems are called trees. The stem has branches in the upper part, much above the ground.

Long Answer Type Questions

Question 1.
How are herbs, shrubs and trees different from each other?
Answer:
a. Herbs are small non-woody plants with soft stem. These plants are very small in size. These plants usually do not grow more than one metre in height. They have very short life span. These plants do not live for more than two seasons.

b. Shrubs are larger than herbs. These plants are hard and woody. These plants tend to branch near ground level, so many branches are seen rising just above the ground giving them a bushy appearance. Their life span is bigger than herbs but smaller than trees.

c. Trees are fully big plants. They have hard and woody stem. They have a trunk which usually gives out branches and leaves. The branches appear higher up on the stem much above the ground. Trees have a great life-span. They live for many years.

Question 2.
What is leaf venation? Explain the various types of leaf venation with an example for each.
Answer:
The design made by veins in a leaf is called leaf venation. The leaf venation have two main types: a. Reticulate venation: In this type of venation, the veins occur in an irregular way forming a net-like design. Pea plant, neem tree, mango tree, marigold, etc., have reticulate venation, b. Parallel venation: In this venation, the veins in a leaf run parallel to one another on both the sides of the midrib. Wheat, paddy, sugarcane, barley, etc., have parallel venation.

Question 3.
What are roots? Write the various functions of roots. Describe the two types of roots.
Answer:
Roots are the parts of plants which grow below the ground (in the soil). Various functions of roots are:

• Roots prevent the plant from being pulled out easily or blown away by the wind.
• Roots absorb water and minerals from the soil for manufacturing of food.
• Roots help in conservation of soil by holding it together.

The two main types of roots are: Taproot and Fibrous root

• Taproot is the main root from which many branching roots grow sideways. Pea plant, radish, mango, mustard, etc., have taproot.
• Fibrous root is a cluster of thin fibre like roots at the base of the stem. These roots spread out in the plants. Wheat, maize, grass, millet, etc., have fibrous roots.

Question 4.
Explain the structure of a leaf. What are the main functions of a leaf?
Answer:
The main parts of a leaf are:

• Petiole: The part of the leaf by which it is attached to the stem is called petiole.
• Lamina: The broad, green part of the leaf is lamina.
• Veins: There are various types of lines on the leaf which are called veins.
• Midrib: There is a thick vein in the middle of the leaf. This vein is called midrib.

There are following two main functions of a leaf:

• Transpiration: In the form of vapour, extra water comes out of the leaves. This process is called transpiration. It helps in cooling and absorbing water from soil by the roots.
• Photosynthesis: The process, by which leaves prepare their food from water and carbon dioxide, in the presence of sunlight and chlorophyll is called photosynthesis.

Question 5.
Explain how flower becomes a fruit.
Answer:
When the pollen grains fall on stigma, they move down through the tube called style and reach the ovary. In the ovary, the male sex cells present in pollens join with the female sex cells present in ovules. The joining together of male and female sex cells is called fertilization. After fertilization, the ovules grow and become seeds. The ovary of flower grows and becomes a fruit.

Picture-Based Questions

Question 1.
a. Identify the type of roots in figures A and B.

b. Which of the above roots is found in grasses?
Answer:
a. A-Taproot; B-Fibrous root
b. Fibrous root

Question 2.
a. Identify A and B.

b. Which of these is the male part of the flower?
c. Which of these is the female part of the flower?
Answer:
a. A-Stamen, B-Pistil
b. Stamen
c. Pistil

These NCERT Solutions for Class 6 Science Chapter 6 Changes Around Us Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Changes Around Us NCERT Solutions for Class 6 Science Chapter 6

Class 6 Science Chapter 6 Changes Around Us Textbook Exercise Questions and Answers

Question 1.
To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Answer:
Yes, by unfolding the dress we can reverse this change.

Question 2.
You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?
Answer:
No, it cannot be reversed. It is an irreversible change.

Question 3.
Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.

Answer:

Question 4.
A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer:
By erasing the drawing, we can undo the change. For example, if we draw with the help of pencil, we can erase the drawing by using an eraser. Then, it is a reversible change. If we draw using a pen, we cannot erase the drawing. Then this change cannot be reversed.

Question 5.
Give examples to explain the difference between changes that can or cannot be reversed.
Answer:
Examples of Reversible Changes:

1. Melting of ice into water: By freezing the water we can obtain ice again.
2. Folding a paper: By unfolding it, we can undo the change.
3. Flot milk to cold milk: By boiling milk, we can make it warm again.

Examples of Irreversible Changes:

1. Bursting a balloon.
2. Bud becoming a flower.
3. Cutting a wood into wood pieces.

Question 6.
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
Answer:
When water is added to POP, it undergoes a chemical change. Its composition changes and is converted into another substance. Since it is a chemical change, it cannot be reversed.

Question 7.
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
Answer:
Due to water, cement hardens and its composition changes. Chemical changes, in general, are irreversible changes. Hence, it is a chemical change which cannot be reversed.

NCERT Extended Learning Activities And Projects

Question 1.
Take a lemon, a paintbrush and a piece of paper. Cut the lemon and squeeze out its juice in a cup. Dip the brush in the lemon juice and write a message on the paper. Let the paper dry and you find that the letters of your message become invisible. Now, press the paper with hot iron or warm it by holding it above the flame of a candle (Take care that it does not catch fire). As the paper gets warm, invisible letters change into dark brown colour. Identify the changes that can be reversed in this process.
Answer:
Irreversible changes: Cutting and squeezing of lemon, writing message on paper.
Reversible changes: Drying and wetting of the paper.

Question 2.
Observe preparation of dishes at your home. Identify two changes that can be reversed.
Answer:
Do it yourself.

Question 3.
Maintain a record for one year of the seasonal changes in vegetables, clothing, nature and events around you. Identify the changes that can or cannot be reversed.
Answer:
Do it yourself.

Activity 1

Objective: To show that a balloon changes its size and shape on blowing air into it and the change is reversible.
Materials Required: A balloon.
Procedure:

• Take a balloon and blow air in it. Take care that it does not burst.
• Now allow the air to escape from the balloon.

Observations: On blowing, the size and shape of the balloon have changed. It regains its shape when air is released.
Conclusion: It is possible to get the balloon back to its original shape and size. Therefore, it is a reversible change.

Activity 2

Objective: To make a toy aeroplane by folding paper and show that the change is reversible.
Materials Required: A piece of paper.
Procedure:

• Take a piece of paper and fold it to make an aeroplane.
• Now unfold the paper again.

Observation: The sheet of paper has changed into a toy aeroplane. On unfolding, the paper regains original form.
Conclusion: It is a reversible change.

Activity 3

Objective: To show that rolling of roti out of dough is a reversible change.
Materials Required: Dough (kneaded flour) and rolling pin.
Procedure:

• Take a dough and make a small ball of it with hands.
• Roll this ball of dough into a circular roti by using a rolling pin.
• Now, convert this circular roti into small ball again by crumbling.

Observations: The dough rolled into roti was converted back in dough boll.
Conclusion: It is a reversible change.

• Irreversible changes: Changes that cannot be reversed to form the original substance are called irreversible changes. Changing of milk into curd is an irreversible change because curd cannot be turned into milk again.
• Slow changes: Changes which take long time to complete are called slow changes. Growth of plants is a slow change.
• Fast changes: Changes which take short time to complete are called fast changes. For example, burning of candle is a fast change.
• Chemical changes: Changes in which the chemical properties of substances change to form a new substance are called chemical changes. For example, digestion of food.
• Physical changes: Changes in which the physical properties of a substance change and no new substance is formed are called physical changes. For example, melting of candle wax.
• Freezing: Turning of a liquid into solid at low temperature is called freezing. For example, freezing of water into ice.
• Melting: Turning of a solid into liquid when the temperature is high is called melting. For example, melting of ice into water.
• Evaporation: The process of conversion of liquid into vapour at higher temperature is called evaporation. For example, water evaporates in sunlight.
• Condensation: The process of conversion of gas into liquid is called condensation.
• Contraction: A phenomenon in which a substance shrinks or changes its shape is called contraction.
• Expansion: Many substances expand on heating. This property is used to fix metal rim on wooden wheels or wooden handles in certain tools. In such tools, iron blade has a ring in which wooden handle is fitted. The ring is slightly smaller than the handle. It is first heated, due to which it expands and handle is fitted in it easily. On cooling, the shrinks back to original size fitting tightly around the handle.

Class 6 Science Chapter 6 Changes Around Us Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Which type of change ¡s growing of a plant – fast or slow?
Answer:
Slow change.

Question 2.
Do you think that cooking of food is an irreversible change?
Answer:
Yes.

Question 3.
Rolling out roti from dough ball is a slow change or a fast change?
Answer:
Fast change.

Question 4.
Turning of ice into water and water into ice is a reversible change or irreversible change?
Answer:
Reversible change.

Question 5.
Classify the following into slow and fast changes:
a. Burning of paper
b. Spinning of top
c. Melting of ice cream
d. Change of season
Answer:
a. Fast change
b. Fast change
c. Fast change
d. Slow change

Question 6.
Growth of a plant is an irreversible change. Explain.
Answer:
When a plant becomes a tree, it cannot be reversed back into a plant. So, it is an irreversible change.

Question 7.
What do you think that deforestation is an irreversible change or a reversible change?
Answer:
Irreversible change.

Question 8.
Give an example to show that pressure changes the shape of a material.
Answer:
When an inflated balloon is pressed between two hands, its shape and size change.

Question 9.
Give an example to show that metal contracts on cooling?
Answer:
An electric wire becomes tight during winters and sag a little during summers. It proves that metal contracts on cooling.

Question 10.
Define: a. evaporation, b. condensation and c. freezing.
Answer:
a. The process of conversion of liquid into vapour is called evaporation.
b. The process of conversion of gas into liquid is called condensation.
c. The change of state from liquid to solid is called freezing.

Question 11.
What are the different ways in which changes can be caused?
Answer:
By mixing, by applying force, by heating and by cooling.

Question 12.
What do you mean by expansion?
Answer:
Expansion is a phenomenon in which a substance expands or changes its shape.

Short Answer Type Questions

Question 1.
Give the characteristics of physical changes.
Answer:

• No new substances are formed.
• Products are identical to reactants in chemical properties.
• These changes are generally reversible.

Question 2.
Give the characteristics of chemical changes.
Answer:

• Properties of product are different from the reactants.
• Most of the chemical changes are irreversible.
• Loss or gain of energy is involved in a chemical change.

Question 3.
Differentiate between physical changes and chemical changes with examples.
Physical change
Answer:

Question 4.
Explosion of cracker is an irreversible change. How?
Answer:
Explosion of a cracker is an irreversible change because once crackers are burnt, they cannot be converted back to their original form.

Question 5.
How candles of different shapes are made?
Answer:
Molten wax is poured in desired mould and a wick is placed in it. Then it is cooled. This is how we get candles of different shapes.

Question 6.
State a few examples each for slow changes and fast changes.
Answer:
Examples of slow changes:

• Germination of seed
• Rusting of iron
• Curdling of milk

Examples of fast changes:

• Burning of candle
• Burning of paper
• Inflating a tire

Question 7.
Formation of clouds is usually a physical change. Justify the statement.
Answer:
The formation of clouds is a physical change because there is a phase transformation cycle of natural water from liquid to gas and then, gas to liquid. Hence, the property of water never changes.

Question 8.
How do we convert milk into curd and what type of change is it?
Answer:
The warm milk is taken in a vessel and a small quantity of curd is added into it. The milk is stirred and it is kept aside for few hours without any disturbance. Finally, the milk is converted into curd. However, curd formed cannot be converted into milk again indicating that it is an irreversible change.

Question 9.
What will be the change when sugar is heated?
Answer:
When sugar is continuously heated, a black powdery substance is formed which is called charcoal. Since a new product is formed, it is termed to be a chemical change.

Question 10.
Rolling of roti from dough is a reversible change. Explain.
Answer:
Take some dough and make a ball of it. Roll this ball of dough into a circular shape by using a rolling pin. Now, if we want, we can convert this rolled roti back into the ball of dough. This proves that the rolling of roti out of dough is a reversible change.

Long Answer Type Questions

Question 1.
Why making statues out of plaster of Paris is an irreversible and chemical change?
Answer:
Making statues out of plaster of Paris is an irreversible and chemical change because Plaster of Paris has a property of setting into a hard mass on getting mixed with water due to the formation of a new compound. The hard mass cannot be converted back into the previous plaster of Paris. Hence, it is an irreversible chemical change.

Question 2.
How is inflating a balloon different from bursting an inflated balloon?
Answer:
Inflating a balloon is an example of a reversible change whereas bursting a balloon is an irreversible change. When we blow air into a balloon, its shape and size changes. But it regains its original form when the air is allowed to escape. On the other hand, a burst balloon cannot be changed back to the original form.

Question 3.
What are desirable and undesirable changes? Explain with examples.
Answer:
Desirable changes: Those changes which are desired to occur, that is, we want them to take place are known as desirable changes. Example: ripening of fruits, germination of seeds, etc.

Undesirable changes: Those changes which we do not want to take place are called undesirable changes. Example: rusting of iron, souring of milk, rotting of fruits, etc.

Question 4.
The burning of paper is said to be an irreversible change whereas the boiling of water is known as reversible change. Give reason.
Answer:
The paper converts into ash on burning which we cannot combine to form the original piece of paper again. Therefore, burning of paper is said to be an irreversible change. On the other hand when we boil water by heating, then it changes into steam. On cooling, the steam, it again converts into water by condensation which is a reversible change. Thus, burning of paper is said to be an irreversible change whereas the boiling of water is known as reversible change.

Question 5.
When is a change said to have taken place in a material? Explain with the help of an example.
Answer:
The things around us have certain properties such as state (solid, liquid, gas), position, shape, size, colour, temperature, composition and structure, etc. When one or more properties of a thing become different, the changes in it have taken place. Changes involve different kinds of alterations in the things. When a change takes place, there may be change in the state, position, shape, size, colour, temperature, composition or structure of the material of the object. Example: when ice melts, it forms water. Ice is a solid, whereas water is a liquid. So, the melting of ice involves a change in state (from solid to liquid state).

Picture-Based Questions

Question 1.
Observe the given pictures and answer the following questions:

a. What type of change it is – physical or chemical?
b. Can this change be reversed?
c. Can this change be reversed after roti is cooked on flame?
Answer:
a. Physical change
b. Yes
c. No

Question 2.
Observe the given picture and answer the questions that follow:

a. Name the process by which above change takes place.
b. Name the process by which this change can be reversed.
Answer:
a. Melting
b. Freezing

These NCERT Solutions for Class 6 Science Chapter 5 Separation of Substances Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Separation of Substances NCERT Solutions for Class 6 Science Chapter 5

Class 6 Science Chapter 5 Separation of Substances Textbook Exercise Questions and Answers

Question 1.
Why do we need to separate different components of a mixture? Give two examples.
Answer:
Among different components of mixture there are many substances which are harmful or not useful for us. To remove these harmful or useless components we need to separate them. For example:

1. Tea leaves are separated from liquid with a strainer while preparing tea.
2. Grain is separated from stalks, while harvesting.

Question 2.
What is winnowing? Where is it used?
Answer:
The process of separating a mixture of light and heavy particles using wind is called winnowing. For example, separating wheat from chaff. Winnowing is used when one components is lighter than the other. The wind blows away chaff while the grain forms separate pile.

Question 3.
How will you separate husk or dirt particles from a given sample of pulses before cooking?
Answer:
Husk or dirt particles can be separated by winnowing, being lighter they will fly away from pulses. Dirt particles can also be separated by handpicking.

Question 4.
What is sieving? Where is it used?
Answer:
Sieving is a process of separation of particles of different sizes using a sieve. Small and fine sieves are used in the kitchen to separate bran and other impurities from flour. The impurities remain on the sieve and the flour passes through. Bigger sieves are used at construction sites to separate pebbles and stones from sand.

Question 5.
How will you separate sand and water from their mixture?
Answer:
We separate sand and water by sedimentation and decantation method. First we leave this mixture for some time. After sometime, the sand which is heavier is settled down at the bottom. After that we will pour water into another container and the mixture will be separated.

Question 6.
Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer:
It is possible to separate sugar mixed with wheat flour. The mixture of sugar and wheat flour can be separated by strainer and sugar being bigger in size remains on the strainer. Thus, sugar can be separated from the mixture of sugar and wheat flour.

Question 7.
How would you obtain clear water from a sample of muddy water?
Answer:
We can separate clear water from muddy water by filtration process. A filter paper is one such filter that has very fine pores in it. A filter paper folded in the form of a cone is fixed in a funnel. The mixture is then poured on the filter paper. Solid particles in the mixture do not pass through it and remain on the filter.

Question 8.
Fill in the blanks.
a. The method of separating seeds of paddy from its stalks is called ……………..
b. When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ……………..
c. Salt is obtained from seawater by the process of ……………..
d. Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called ……………..
Answer:
a. threshing
b. filtration
c. evaporation
d. sedimentation and decantation

Question 9.
True or False?
a. A mixture of milk and water can be separated by filtration.
b. A mixture of powdered salt and sugar can be separated by the process of winnowing.
c. Separation of sugar from tea can be done with filtration.
d. Grain and husk can be separated with the process of decantation.
Answer:
a. False
b. False
c. False
d. False

Question 10.
Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?
Answer:
We should add ice after dissolving sugar. When the temperature is high, then more sugar can be dissolved. After mixing ice, it gets cool and less sugar will dissolve in it.

NCERT Extended Learning Activities and Projects

Question 1.
Visit a nearby dairy and report about the processes used to separate cream from milk.
Answer:
Do it yourself.

Question 2.
You have tried a number of methods to separate impurities like mud from water. Sometimes, the water obtained after employing all these processes could still be a little muddy. Let us see if we can remove even this impurity completely. Take this filtered water in a glass. Tie a thread to a small piece of alum. Suspend the piece of alum in the water and swirl. Did the water become clear? What happened to the mud? This process is called loading. Talk to some elders in your family to find out whether they have seen or used this process.
Answer:
Do it yourself.

Activity 1

Objective: To prepare a saturated salt solution and study the effect of temperature.
Materials Required: Water, glass, salt, spoon.
Procedure:

• Dissolve salt in water by continuous stirring.
• After some time, more salt will not be able to dissolve in water. This become a saturated solution.
• Now heat the water and try dissolving more salt.

Observations: More salt can be dissolved in a saturated solution on heating.
Conclusion: On increasing temperature, solubility of substances also increase.

Need for Separation: The constituents of mixtures need to be separated for the following reasons:
i. To remove undesirable substances: Before we use a substance, we need to separate the harmful substance that may be mixed with it. For example, we need to separate the impurities from ordinary water to make it potable water.
ii. To obtain desirable substances: Sometimes, we need to separate even useful components if we need to use them separately. For example, we separate petrol, kerosene and diesel from petroleum (crude oil).
iii. To obtain highly pure substances: While producing a medicine, it is essential to remove all harmful impurities from the substance so that it can be used as medicine. But in this case, the impurity has to be removed without any loss or wastage of the substance.

Principle of Separation: The constituents of a mixture do not lose their original properties such as particle size, density, melting point, boiling point, etc. This property is used in separation methods.

Methods of Separation: Different methods are used for separating substances that are mixed together. Let us read about some common methods that are used.
i. Handpicking: This method of handpicking can be used for separating slightly larger-sized impurities such as the pieces of dirt, stone and husk from wheat, rice or pulses. The quantity of such impurities is usually not very large. In such condition, we find that handpicking is a convenient method of separation.

ii. Winnowing: It is a process used to separate heavier and lighter dust particles or components of a mixture by wind or by blowing air. This method is commonly used by fanners to separate lighter husk particles from heavier seeds of grains. The simplest way is to stand on a higher level and allow the mixture to fall on the ground. The wind blows away the light components while the heavier grains fall down to form a heap. The separated chaff is used as fodder for cattle.

iii. Threshing: The process used to separate grains from stalks is called threshing. In the process of threshing, the stalks are beaten to free grain seeds. This process of threshing can be done with the help of bullock. Machines are generally used to thresh large quantities of grain.

iv. Sieving: It is a method of separation of particles of different sizes using a sieve. Small and fine sieves are used in the kitchen to separate bran and other impurities from flour. The impurities remain on the sieve and the flour passes through. Bigger sieves are used at construction sites to separate pebbles and stones from sand.

v. Magnetic Separation: In this method a magnet is used for picking up iron pieces, nails, pins, etc. from grains or any other commodity. On a larger scale, a powerful magnet is employed for separating scrap iron from non-magnetic waste materials.

vi. Sedimentation and Decantation: The process of settling down of the heavy solids at the bottom, in a mixture of a liquid and an insoluble solid is called sedimentation. The solid particles that settle down during sedimentation are called sediments.

Separation of a mixture of sand and water

The liquid above the sediments is known as the supernatant liquid. The process of pouring out the clear upper liquid without disturbing the sediments is called decantation. The solid particles which are insoluble in a liquid can be separated by decantation. For example, a mixture of sand and water contains sand particles suspended in water. So,sand can be separated from sand-water mixture by the method of sedimentation and decantation.

vii. Filtration: Decantation is not enough for complete separation of a solid-liquid mixture. This can be done better by filtration in which the mixture is dropped on a porous material known as filter.

The liquid passes through the filter and comes down as filtrate. The insoluble solid left behind is known as residue. In this way, a mixture of an insoluble solid in a liquid is separated into the solid residue and clear filtrate.

Activity 2

Objective: To purify a sample of muddy water by the process of filtration.
Materials Required: Soil, water, glass, filter paper, funnel, clamp stand and beaker.
Procedure:

• Mix some soil with water in a glass.
• Make a filter paper cone and set it in a funnel.
• Arrange the apparatus as shown below.
• Allow water into the funnel through filter paper get collected in the beaker.

Observations: Soil residue is left behind in the funnel and clear water is obtained as filtrate in the beaker.
Conclusion: Muddy water can be purified by filtration.

viii. Loading: Loading is a method in which a special substance called alum is used to load the suspended particles to make them heavy and increase their sedimentation speed. For example, the particles of clay in muddy water are very fine and their sedimentation takes a very long time.

Alum is used to load suspended clay particles in water. The dissolved particles of alum load the fine particles of clay in water. They become heavier and settle down very fast. The clear water on top is then decanted or filtered.

ix. Centrifugation: All rotating bodies experience centrifugal force. The principle of centrifugal force is applied for separation of solids and liquids. This method is called centrifugation. This method is of great value in case of separating thin pastes from thick pastes, where filtration is not possible.

Cream separating machines are used in dairies. In this machine, milk is rotated at a high speed. Cream being lighter, collects towards the centre. The milk being heavier settles down below the cream layer. The two are then taken out from two separate taps,

x. Evaporation: The process of conversion of water into its vapour is called evaporation. This process takes place continuously wherever water is present. For example, sea water contains many types of salts mixed in it. One of these salts is the common salt. When sea water is allowed to stand in shallow pits, water gets heated by sunlight and slowly turns into water vapour.

After few days, the water evaporates completely leaving behind the dry solid particles. The common salt is then obtained from this mixture of solid particles by further purification.

xi. Condensation: Water is present in air in the form of water vapour. When water vapour touches the cold surfaces of the glass or other objects, it changes into water droplets. This change of water vapour into water is called condensation.

Use of more than one method of separation: The method to be used for separating a mixture into its components depends on the nature of components.

Some of the mixtures can be separated by a single method but various mixtures can be separated into individual components by using a combination of various methods. These methods are applied turn by turn. Suppose you are given a mixture of sand, iron fillings, common salt, solid salt and naphthalene. You can separate its components as follows:
Iron fillings: by magnetic separation
Naphthalene: by sublimation

Salt and sand are dissolved in water. Salt is soluble but sand being insoluble, settles and can be separated by sedimentation, decantation followed by evaporation of salt water.

Class 6 Science Chapter 5 Separation of Substances Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Name any two methods used for separation of substances.
Answer:
Threshing and filtration.

Question 2.
Which method is used to separate stones from grains on small scale?
Answer:
Handpicking.

Question 3.
How does the farmer separate grain seeds from bundles of stalk?
Answer:
By threshing, farmer can separate grain seeds from bundles of stalk.

Question 4.
Which method is used to separate heavier and lighter components of a mixture by wind or blowing air?
Answer:
Winnowing.

Question 5.
What is decantation?
Answer:
The process in which water is removed when heavier component of mixture settles is called decantation.

Question 6.
Which method of separating tea leaves from prepared tea is better: filtration or decantation?
Answer:
Filtration.

Question 7.
What is evaporation?
Answer:
The process of conversion of water into its vapour at normal temperature is called evaporation.

Question 8.
How can sand be separated from water?
Answer:
Sand can be separated from water by sedimentation and decantation.

Question 9.
We dissolve salt in water. By what way the same amount of water could be made to dissolve more salt before getting saturated?
Answer:
On heating the water.

Question 10.
Define condensation.
Answer:
The process in which a gas changes into its liquid form is called condensation.

Question 11.
What happens when a saturated solution is heated?
Answer:
It becomes unsaturated.

Question 12.
What is the effect of temperature on the solubility of solids in liquids?
Answer:
The solubility of solids in liquids increases with increase in temperature.

Question 13.
Mention one purpose of separating the constituents of a mixture.
Answer:
To remove the unusual or harmful compound and to obtain the useful component.

Question 14.
Name the process by which water is separated from rice and pulses after washing them.
Answer:
The water is separated from rice and pulses by decantation.

Short Answer Type Questions

Question 1.
What is evaporation? Give one large scale use of the process of evaporation.
Answer:
The process of conversion of water into vapour is called evaporation. This process takes place continuously where water is present.

The process of evaporation is used on a large scale to obtain common salt from sea water. Sea water is trapped in shallow lakes and allowed to stand there. The heat of sun gradually evaporates water in the shallow lakes and common salt is left behind as a solid.

Question 2.
What do you mean by decantation? What is its use?
Answer:
Decantation is a process by which we can remove a liquid without disturbing the solid settled down in the bottom. This method can be used to separate mixture of sand and water

Question 3.
a. State one use of the method of winnowing.
b. Give one use of the handpicking method of separating mixtures in daily life.
Answer:
a. The method of winnowing is used to separate husk from various types of grains like wheat, rice, etc.
b. The method of handpicking is usually used to separate undesirable substances, such as small pieces of stones from wheat, rice and pulses.

Question 4.
The mixture of a powdered white solid A and a liquid B can be separated by filtration. The solid A is left behind on the filter paper but clear liquid B passes through the filter paper and collects in the beaker kept below.
a. Name some solid which could be like A.
b. Name the liquid which B could be.
c. What name is given to the solid left on the filter paper?
d. What name is given to the clear liquid collected in the beaker?
Answer:
a. Chalk powder
b. Water
c. Residue
d. Filtrate

Question 5.
Name the method that should be used to separate the following mixtures:
a. Grain from wheat flour
b. Grain from the stalks
c. Small black pebbles from a plateful of pulses
d. Wheat from chaff
Answer:
a. Sieving
b. Threshing
c. Handpicking
d. Winnowing

Question 6.
How will you prepare cheese (paneer)?
Answer:
For making cheese, a few drops of lemon juice are added to milk as it boils. This gives a mixture of particles of solid cheese and liquid. The cheese is then separated by filtering the mixture through a fine cloth or strainer.

Question 7.
What is mixture?
Answer:
When two or more than two substances are mixed together in any ratio then it is called a mixture.

Question 8.
What is a homogeneous mixture?
Answer:
A mixture in which the various components are uniformly mixed or dissolved and each part of the mixture has the same properties is called a homogenous mixture.

Question 9.
What is a heterogeneous mixture?
Answer:
A mixture whose components are not uniformly mixed or dissolved and hence each part of the mixture does not have the same properties is called a heterogeneous mixture.

Long Answer Type Questions

Question 1.
What is filtration? Give an example.
Answer:
Decantation is not enough for complete separation of a solid-liquid mixture. This can be done better by filtration, in which the mixture is dropped on a porous material known as filter. The liquid passes through the filter and comes down as filtrate. The insoluble solid left behind is known as residue. When you make tea, you filter it through a strainer having wire gauze. The tea extract comes down as the filtrate and the boiled tea leaves are left behind as the residue.

Question 2.
Why is loading used to separate suspended impurities? Explain.
Answer:
Sometimes water of a river or canal is muddy or turbid due to hanging of very fine particles of clay. They cannot be removed by decantation or filtration. In such a case loading is useful.

Loading: Loading is a method in which a special substance called alum is used to load the suspended particles to make them heavy and increase their sedimentation speed. For example, the particles of clay in muddy water are very fine and their sedimentation takes a very long time.

Alum is used to load suspended clay particles in water. The dissolved particles of alum load the fine particles of clay in water. They become heavier and settle down very fast. The clear water on top is then decanted or filtered.

Question 3.
Water is a universal solvent. Give reason.
Answer:
Water is a universal solvent because it can dissolve a large number of substances in it. Water is essential to our body in the process of digestion. Several waste materials in our body get dissolved in water and are then excreted. A number of chemical reactions occur inside our body. They all occur in the presence of water. Water can dissolve almost all substances, hence is called universal solvent.

Picture-Based Questions

Question 1.
a. Identify the pictures A and B:

b. Which of the above is used on a large scale separation of grains from chaff?
Answer:
a. A-Handpicking; B-Winnowing
b. Winnowing

Question 2.
Observe the picture and answer the questions.

a. Identify the seperation technique?
b. Where is it being used.
Answer:
a. Sieving
b. It is being used by a worker at construction site to separate pebbles and stones from sand.