In-text Questions (Page 248)<\/span><\/p>\nQuestion 1.
\nWhat are the disadvantages of fossil fuels ?
\nAnswer:
\nDisadvantages of fossil fuels :
\n(i) It is a non-renewable source of energy. If we were to continue consuming these courses as such fast rates, we would soon face energy crisis.<\/p>\n
(ii) Fossil fuels cause air pollution. The oxides of carbon, nitrogen and sulphur that are released on burning fossil fuels are acidic oxides. These lead to acid rain which affects our water and soil resources.<\/p>\n
Question 2.
\nWhy are we looking at alternate sources of energy ?
\nAnswer:
\nIn ancient time, wood was the most common source of heat energy. The exploitation of coal and petroleum of energy made the industrialisation possible. The growing demand for energy was largely met by the fossil fuels, coal and petroleum. Our technologies were also developed for using these energy sources. But these fuels were formed over millions of years ago and there are only limited resources. If we were to continue consuming these sources at such alarming rates, we would soon face energy crises, In order to avoid this, we are looking at alternate source of energy.<\/p>\n
Question 3.
\nHow has the traditional use of wind and water energy been modified for our convenience ?
\nAnswer:
\nThe kinetic energy of the wind can be used to do work. This energy was harnessed, by windmills in the past to do mechanical work such as in a water lifting pump. The rotatory motion of windmill is utilised to lift water form a well. But nowadays, wind energy is used to generate electricity. To generate electricity, the rotatory motion of the windmill is used to turn the turbine of the electric generator.<\/p>\n
The kinetic energy of flowing water or potential energy of water at a height can be converted into electricity. The hydropower plants are associated with dams. The water from the high level in the dam is carried through pipes, to the turbine and thus electricity is generated.<\/p>\n
<\/p>\n
In-text Questions (Page 253)<\/span><\/p>\nQuestion 1.
\nWhat kind of mirror concave, convex or plain-would Be best suited for use in a solar cooker ? Why?
\nAnswer:
\nPlane mirror, because it is a good reflector and a temperature inside the cooker goes upto 100\u00b0 to 140\u00b0c. This heat is sufficient to cook the food easily. If other mirrors are used, the temperature is very low or high. At low temp, food is not cooked well and at very high temperature food is damaged or looses its taste.<\/p>\n
Question 2.
\nWhat are the limitations of the energy that can be obtained form the oceans ?
\nAnswer:<\/p>\n
\n- The energy potential from the oceans is quite large, but efficient commerical exploitation is difficult.<\/li>\n
- The setting of a ocean power plant is very difficult.<\/li>\n<\/ol>\n
Question 3.
\nWhat is geothermal energy ?
\nAnswer:
\nThe energy which is obtained due to geological changes is called geothermal energy.<\/p>\n
Question 4.
\nWhat are the advantages of nuclear energy ?
\nAnswer:<\/p>\n
\n- It does not create air pollution.<\/li>\n
- A small amount of fuel is able to produce a tremendous amount of energy.<\/li>\n
- The nuclear energy produced can be converted into electricity easily.<\/li>\n
- Once the nuclear fuel is loaded into a nuclear power plant, than it will go on releasing energy for two or three years.<\/li>\n<\/ul>\n
In-text Questions (Page 253)<\/span><\/p>\nQuestion 1.
\nCan any source of energy be pollution fee ? Why or why not ?
\nAnswer:
\nC. N. G is considered as a pollution free fuel because it does not produce any poisonous or polluting gas on burning and it also does not produce particulate matter on burning. Solar energy is also in the same category. A source of energy be considered polluted if it produce poisonous gaseous and particulates matter on burning eg. coal.<\/p>\n
Question 2.
\nHydrogen has been used as a rocket fuel. Would consider it a cleaner fuel than CNG? Why or why not ?
\nAnswer:
\nHydrogen has been used as a rocket fuel. The chemical reaction involved is :
\nH2<\/sub>(g) + O2<\/sub> (g) H2<\/sub>O (l) + 286 kJ<\/p>\nIt is considered a cleaner fuel than C. N. G, because its combustion product is water. So hydrogen as a fuel provides pollution free atmosphere.<\/p>\n
<\/p>\n
In-text Questions (Page 254)<\/span><\/p>\nQuestion 1.
\nName Two energy sources that you would consider to be renewable. Give reasons for your choices.
\nAnswer:
\nRenewable sources :<\/p>\n
\n- Wind energy.<\/li>\n
- Water energy Because if these sources are consumed continously, they will not get exhausted.<\/li>\n<\/ol>\n
Question 2.
\nGive the name of two energy sources that you would consider to be exhaustible. Give reasons for your choice.
\nAnswer:
\nExhaustible energy sources :
\n(i) Coal, (ii) Petroleum.
\nBecause if these sources are consumed, they will get exhausted.<\/p>\n
Class 10 Science Chapter 14 Sources of Energy Textbook Questions and Answers<\/h3>\n
Page no. 254-255<\/span><\/p>\nQuestion 1.
\nA solar water heater cannot be used to get hot water on:
\n(a) a sunny day
\n(b) a cloudy day
\n(c) a hot day
\n(d) a windy day
\nAnswer:
\n(b) A cloudy day.<\/p>\n
Question 2.
\nWhich of the following is not an example of a biomass energy source :
\n(a) wood
\n(b) gobar-gas
\n(c) atomic energy
\n(d) coal.
\nAnswer:
\n(c) Atomic energy<\/p>\n
Question 3.
\nMost of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the sun’s energy:
\n(a) geothermal energy
\n(b) wind energy
\n(c) fossil fuels
\n(d) bio-mass.
\nAnswer:
\n(a) Geothermal energy.<\/p>\n
<\/p>\n
Question 4.
\nCompare and constrast fossil fuels and the sun as direct sources of energy.
\nAnswer:
\nFossils fuel :<\/p>\n
\n- It is a non-renewable sources.<\/li>\n
- Fossil fuel are formed in nature long ago under special conditions of temperature and pressure.<\/li>\n
- It is exhaustable source of energy.<\/li>\n
- Coal and petroleum are the main fossils fuel.<\/li>\n
- It causes pollution.<\/li>\n<\/ol>\n
Solar energy or sun as direct source of energy:<\/p>\n
\n- It is a renewable source of energy energy.<\/li>\n
- The sun is the ultimate source of all forms of energy available on earth.<\/li>\n
- It is in exhaustible source of energy.<\/li>\n
- Solar energy, wind energy Ocean energy and hydro energy are the main forms of sun energy.<\/li>\n
- It does not causes pollution.<\/li>\n<\/ol>\n
Question 5.
\nCompare and constrast bio-mass and hydroelectricity as sources of energy
\nAnswer:
\nBio-mass: Wood has been used as a fuel for a long time. If we can ensure that enough trees are planted, a continuous supply of fire-wood can be assured. We are also familiar with the use of cow-dung cakes as a fuel. Given the large live-stock population in India, this can also assure us a steady source of fuel. Since these fuels are plant and animal products, the source of these fuels is said to be bio-mass. These fuels, however do not produce much heat on burning and a hot of smoke is given out when they are burnt. So, technological inputs to improve the efficiency of these fuels are necessary. When wood is burnt in a limited supply of oxygen, charcoal is formed. Charcoal bums without flame, is comparatively smokeless and has a higher heat generation efficiency.<\/p>\n
Similarly cow dung, various plant materials like the residue after harvesting the crops, vegetable waste and sewage are decomposed in the absence of oxygen to give biogas. Biogas is an excellent fuel as it contains up to 75% methane. It has high heat capacity, it burns without smoke.<\/p>\n
Hydro-electricity: The flowing water has both kinetic as well as potential energy The energy of the flowing water is called hydro-energy. It is an important renewable source of energy. The hydro energy has been traditionally used in past for grinding of grains just by turning the water wheel. Presently, the hydro energy is used to generate electricity by turning the blades of a turbine. The electricity, thus generated by flowing water is called hydro electricity For generating hydro-electricity, a dam is constructed across a river to block the flow of water in the reservoir behind the dam. The huge turbine blades are turned by the water as it flows down from the dam. The hydro-electricity generated by flowing water is transmitted to far away from the power station for supply to factories and homes through conducting wires.<\/p>\n
Question 6.
\nWhat are the limitations of extracting energy from: (a) the wind ? (b) waves ? (c) tides ?
\nAnswer:
\n(a) Limitations of wind energy:<\/p>\n