Time allowed: 3 hours<\/strong> General Instructions<\/strong><\/span><\/p>\n SECTION-A<\/strong><\/p>\n Question 1.<\/strong> Question 2.<\/strong> Question 3.<\/strong> Question 4.<\/strong> Question 5.<\/strong> Question 6.<\/strong> OR<\/strong><\/p>\n Draw ray diagrams to show the formation of three times magnified (a) real, and (b) virtual image of an object by a convex lens. Mark the positions of O, F, 2F in the diagrams.<\/p>\n Question 7.<\/strong> Question 8.<\/strong> Question 9.<\/strong> Question 10.<\/strong> OR<\/strong><\/p>\n What are the different modes of reproduction seen in unicellular organisms ? Give examples.<\/p>\n Question 11.<\/strong> Question 12.\u00a0<\/strong> Question 13.<\/strong> OR<\/strong><\/p>\n Why is respiration considered an exothermic reaction ? Explain.<\/p>\n Question 14.<\/strong> Question 15.<\/strong> Question 16.<\/strong> Show the positions of pole, principal focus and the centre of curvature in the above ray diagrams.<\/p>\n Question 17.<\/strong> OR<\/strong><\/p>\n Question 18.<\/strong> Question 19.<\/strong><\/p>\n Question 20.<\/strong> Question 21.<\/strong> OR<\/strong><\/p>\n SECTION-B<\/strong><\/p>\n Question 22.<\/strong> Question 23.<\/strong> Question 24.<\/strong> Question 25.<\/strong> Question 26.<\/strong> OR<\/strong><\/p>\n Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.<\/p>\n Question 27.<\/strong> ANSWERS<\/strong><\/span> Answer 1.<\/strong> Answer 2.<\/strong> Answer 3.<\/strong> Answer 4.<\/strong> Answer 5.<\/strong> Answer 6.<\/strong> OR<\/strong><\/p>\n (a)<\/strong> To get three times magnified real image,the object has to be placed between F1<\/sub> and 2F1 (b)<\/strong>\u00a0To get three times magnified virtual image, the object is placed between F1<\/sub> and the optical centre O. <\/p>\n Answer 8.<\/strong> Examples of combination reaction are: Answer 9.<\/strong> Answer 10.<\/strong> OR<\/strong><\/p>\n The different modes of reproduction seen in unicellular organisms are fission and budding. Answer 11.<\/strong><\/p>\n Answer 12.<\/strong> Answer 13.<\/strong> OR<\/strong><\/p>\n In human beings, energy is obtained from the food we eat. During digestion of food, large molecules of food like carbohydrates, proteins etc. are broken down into simpler substances such as glucose, amino acids etc. Glucose combines with oxygen in the cells and provides energy. The special name of this combustion reaction, Since energy is released in the whole process, it is an exothermic process.<\/p>\n Answer 14.<\/strong> Answer 15.<\/strong> Answer 16.<\/strong> Answer 17.<\/strong> OR<\/strong><\/p>\n (a)<\/strong> By the addition reaction of unsaturated hydrocarbon with halo atom in the presence of catalyst.<\/p>\n HC = CH + H2<\/sub> \\(\\xrightarrow [ 5700K ]{ Ni }\\) CH3<\/sub> – CH3<\/sub>
\nMaximum marks : 80<\/strong><\/p>\n\n
\nName one flower that has both stamen and pistil.\u00a0\u00a0[1]<\/strong><\/p>\n
\nWhich enzyme is present in saliva and what is its function ?\u00a0\u00a0[1]<\/strong><\/p>\n
\nWhat is metallic lustre ? How are metals found in nature ? What is gangue ?\u00a0\u00a0[2]<\/strong><\/p>\n
\nWhat is accommodation of the eye ? When does the maximum accommodation of a normal eye reached.\u00a0\u00a0[2]<\/strong><\/p>\n
\n“Burning of fossil fuels results in global warming.” Give reasons to justify this statement.\u00a0\u00a0[2]<\/strong><\/p>\n
\nDefine absolute and relative refractive index ?\u00a0\u00a0[3]<\/strong><\/p>\n
\nAn electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has
\na current rating of 5 A. What results do you expect ? Explain.\u00a0\u00a0[3]<\/strong><\/p>\n
\nWhat are the indicators that suggest that a chemical reaction has taken place ? Give two examples of combination reaction.\u00a0\u00a0[3]<\/strong><\/p>\n
\nWhat happens when a magnesium ribbon is burnt in air ? What kind of change is it ? Why magnesium ribbon be cleaned before burning in air ?\u00a0\u00a0[3]<\/strong><\/p>\n
\nWhat are homologous organs ? What do they point to ? Give an example.\u00a0\u00a0[3]<\/strong><\/p>\n
\nCompare anaerobic and aerobic respiration.\u00a0\u00a0[3]<\/strong><\/p>\n
\n(a) What is a coulomb ?\u00a0\u00a0[3]<\/strong>
\n(b) Define electric circuit. Give the circuit diagram of a typical electrical circuit.<\/p>\n
\nWhy should a chemical equation be balanced ? Balance the following equations:\u00a0\u00a0[3]<\/strong>
\n(a) HNO3<\/sub> + Ca(OH)2<\/sub> \u2192 Ca(NO3<\/sub>)2<\/sub> + H2<\/sub>O
\n(b) NaCl + AgNO3<\/sub> \u2192 AgCl + NaNO3<\/sub><\/p>\n
\nWhat was Chipko Andolan ? How did this Andolan ultimately benefit the local people and the environment ?\u00a0\u00a0[3]<\/strong><\/p>\n
\nHow is food digested in the small intestine ? What are the different substances that act upon and break down carbohydrates, proteins and fats.\u00a0\u00a0[3]<\/strong><\/p>\n
\nIt is desired to obtain an erect image of an object, using concave mirror of focal
\nlength of 12 cm.\u00a0\u00a0[5]<\/strong><\/p>\n\n
\nBoth soap and detergent are some type of salts. What is difference between them ? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water ? List two problems that arise due to the use of detergents instead of soaps.\u00a0\u00a0[5]<\/strong><\/p>\n\n
\nDraw a neat labelled diagram of the human brain. Write down the functions of the cerebellum and medulla oblongata ?\u00a0\u00a0[5]<\/strong><\/p>\n\n
\nWhat is the major difference between Mendeleev’s periodic table and the Modem Periodic Table ? Discuss the trend in the modem periodic table with regard to valency and atomic size.\u00a0\u00a0[5]<\/strong><\/p>\n
\nWhat is a good source of energy ? Name some non-conventional sources of energy that man is trying to use now-a-days. What will be the environmental consequence of these energy
\nsources that man needs to be careful about ?\u00a0\u00a0[5]<\/strong><\/p>\n\n
\nWhen water is slowly added to calcium oxide or quick lime in a beaker the solution turns hot. Why ?\u00a0\u00a0[2]<\/strong><\/p>\n
\nWhy are tarnished copper vessels washed in lemon or tamarind juice ?\u00a0\u00a0[2]<\/strong><\/p>\n
\nA student was asked to observe the permanent slide of yeast showing asexual reproduction. What was the process he saw ? Let him draw the diagram.\u00a0\u00a0[2]<\/strong><\/p>\n
\nName the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Write the first step from where such a type of reproduction begins. Draw first two stages of this reproduction.\u00a0\u00a0[2]<\/strong><\/p>\n
\nTina got her eyes tested and doctor recommended -3D lens for correcting her vision.\u00a0\u00a0[2]<\/strong><\/p>\n\n
\nIf a student wants to connect four cells of 1.5 V each to form a battery of voltage 6 V, then how would he draw the symbol of the battery ?\u00a0\u00a0[2]<\/strong><\/p>\n
\nSECTION-A<\/strong><\/p>\n
\nHibiscus plant has both stamen and pistil.<\/p>\n
\nSalivary amylase is present in saliva and its function is to break down starch into sugar.<\/p>\n
\nMetallic lustre refers to the shining appearance of metals in their pure state. Metals are usually found in the form of minerals in nature. A mineral contains a high percentage of the metal. These minerals are called ores. Ores mined from the earth contain a lot of impurities like soil, sand etc. called gangue.<\/p>\n
\nThe ability of an eye to focus the distant objects as well as the nearby objects on the retina by changing the focal length of its lens is called accommodation. The maximum accommodation of a normal eye is reached when the object is at a distance of about 25 cm from the eye.<\/p>\n
\nBurning of fossil fuels produces green house gases like CO, CO2<\/sub> etc. High concentration of these gases in the atmosphere causes insulation, creates green house effect and causes global warming.<\/p>\n
\nAbsolute refractive index:<\/strong> It is the refractive index of the medium defined with respect to a vacuum. It is the ratio of the speed of light in vacuum to the speed of light in the medium. It is always greater than one.
\nRelative refractive index:<\/strong> It is the refractive index of the medium defined relative to another medium. It is the ratio of speed of light in one medium (other than vacuum or air) to the speed of light in another medium<\/p>\n
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\n<\/sub><\/p>\n
\n![\"CBSE](\"https:\/\/i1.wp.com\/www.ncert-solutions.com\/wp-content\/uploads\/2018\/10\/CBSE-Sample-Papers-for-Class-10-Science-Set-3-2.png?resize=447%2C222&ssl=1\")
\nAnswer 7.<\/strong>
\nAn electric oven of 2 kW rating means it has a total power of 2 x 1000 = 2000 W. Now this is operated in a domestic circuit of 220 V. Hence, the current flowing will be 2000 W\/220 V. This means that the 1 current drawn by the electric oven is 9.09 A which is very high but the fuse in this circuit is only of 5 A capacity. So, when a very high current of 9.09 A flows through the 5 A fuse, the fuse wire will get heated too much, melt and break the circuit, cutting off the power supply.<\/p>\n
\nThe indicators that suggest that a chemical reaction has taken place are as follows :<\/p>\n\n
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<\/p>\n
\nWhen magnesium ribbon is burnt in air, it bums with a dazzling white flame. It undergoes oxidation and forms magnesium oxide. It is a chemical change irreversible in nature.
\nIt is cleaned before burning in air in order to remove the protective layer of basic magnesium carbon\u00acate from its surface so that it may readily combine with oxygen present in the air to form magnesium oxide.
\n![\"CBSE](\"https:\/\/i0.wp.com\/www.ncert-solutions.com\/wp-content\/uploads\/2018\/10\/CBSE-Sample-Papers-for-Class-10-Science-Set-3-4.png?resize=327%2C49&ssl=1\")
<\/p>\n
\nHomologous organs are the organs having the same structure but different functions. They point to a common ancestor. They help to identify an evolutionary relationship between apparently different species. Some examples are the forelimb of a frog, the forelimb of a lizard, the wing of a bird and the hand of humans. However all similarities in organ shape does not imply a common ancestry. If we consider the wings of bats and birds we find they have the same function but different structure. The wing of bat is made up of a fold of skin, the wing of birds is made up of feathers. This means they are not homologous but analogous.<\/p>\n
\nIn Amoeba, cell division leads to the formation of two new individuals. When two individuals are formed it is called binary fission. Binary fission is also seen in Leishmania<\/strong>, When many individuals are formed as in Plasmodium<\/strong> it is called multiple fission. In yeast, many small buds are formed in the parent body which separate and form new individuals.<\/p>\n\n\n
\n Anaerobic respiration<\/strong><\/td>\n Aerobic respiration<\/strong><\/td>\n<\/tr>\n \n (i)<\/strong> It takes place in the absence of oxygen.<\/td>\n It takes place in the presence of oxygen.<\/td>\n<\/tr>\n \n (ii)<\/strong> It usually takes place in fungi during fermen\u00adtation.<\/td>\n It takes place in all plants and animals.<\/td>\n<\/tr>\n \n (iii)<\/strong> Glucose is broken down into ethyl alcohol and carbon dioxide.<\/td>\n Glucose is completely oxidised to form carbon dioxide and water.<\/td>\n<\/tr>\n \n (iv)<\/strong> Small amount of energy is released here.<\/td>\n Plenty of energy is released which is stored as ATP-Adenosine Tri Phosphate
\nmolecules.<\/td>\n<\/tr>\n\n (v)<\/strong> The process is often toxic to both plants and animals.<\/td>\n The process is non-toxic to both plants and animals<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n(a) Coulomb is the S.I. unit of electric charge. It is equivalent to the charge contained in
\n6 x 1018<\/sup> electrons.
\n(b) A continuous conducting path consisting of wires and other resistances (like electric bulb, etc.) and a switch, between the two terminals of a cell or a battery along which an electric current flows, is called an electric circuit.
\nThe circuit diagram of a typical electrical circuit is given below:
\n![\"CBSE](\"https:\/\/i2.wp.com\/www.ncert-solutions.com\/wp-content\/uploads\/2018\/10\/CBSE-Sample-Papers-for-Class-10-Science-Set-3-5.png?resize=341%2C201&ssl=1\")
<\/p>\n
\nAs per the law of conservation of mass, mass can neither be created nor be destroyed in a chemical reaction. So the total mass of the elements present in the products of a reaction has to be equal to the total mass of the elements in the reactants. This means the number of atoms of each element remains the same before and after a chemical reaction.<\/p>\n\n
\nChipko movement means “hug the tree” it is one of the movements in India to conserve biodiversity. It was started by Sunder Lai Bahuguna. This movement originated in Reni Village of Garhwal. To stop the contractor from falling of trees women in the village clasped to the trunk of the tree. Its benefits were:<\/p>\n\n
\nand maintained ecological balance.<\/li>\n
\nThe small intestine is the part where complete digestion of carbohydrates, proteins and fats takes place. The secretions of the liver and pancreas reach the small intestine. The digested food from the stomach is acidic and it mixes with the bile juice from the liver to change to alkaline medium for the pancreatic enzymes to act on it. Bile salts break down the big fat globules into smaller parts for further digestion. Pancreatic juice has enzymes like trypsin to act on proteins and lipase to act on emulsified fats. The walls of the small intestine have glands that secrete the intestinal juice. They convert protein to amino acids, carbohydrates to glucose and fats into fatty acids and glycerol.<\/p>\n
\n(a) Range of distance should be 0 cm to < 12 cm.
\n(b) The image will be larger than the object.
\n![\"CBSE](\"https:\/\/i2.wp.com\/www.ncert-solutions.com\/wp-content\/uploads\/2018\/10\/CBSE-Sample-Papers-for-Class-10-Science-Set-3-6.png?resize=534%2C202&ssl=1\")
\n(c) Image will be formed at a distance of 24 cm in front of the mirror
\n![\"CBSE](\"https:\/\/i1.wp.com\/www.ncert-solutions.com\/wp-content\/uploads\/2018\/10\/CBSE-Sample-Papers-for-Class-10-Science-Set-3-7.png?resize=334%2C211&ssl=1\")
<\/p>\n
\nSoaps are made up of sodium or potassium salts of long chain carboxyic acids.
\nDetergents are sodium salts of bezene sulphonic acid.
\nCleansing action of soaps :
\nOne part of soap is ionic, it is hdrophilic and dissolves in water. The other part is non-ionic consists of hydrocarbon chain and is hydrophobic in nature which is insoluble in water but dissolves in oil. Thus, soap molecules arrange themselves in the form of a micelle. On rinsing with water, soap is washed off, lifting the oily dirt particles with it. Soap does not form lather in hard water because of the reaction of soap with Ca2+<\/sup>\u00a0and Mg2+<\/sup> ions present in hard water which forms insoluble precipitate called as scum.
\nProblems due to the use of detergents are:<\/p>\n\n
\nR2<\/sub>C = CR2<\/sub> + H2<\/sub> \\(\\underrightarrow { Ni } \\) R