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CBSE Sample Papers for Class 10 SA2 Science Solved 2016 Set 3
SECTION-A
1. Write the total number of periods in modern periodic table.
2. What is a gene ?
3. The first trophic level in a food chain is always a green plant. Why ?
4. Accumulation of harmful chemicals in our bodies can be avoided. Explain how this can be
achieved ? (HOTS)
5. In an area A, the leaf material available to beetles was very less. What are the two consequences
seen in the beetles ? (HOTS)
6. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should the position of the object be relative to the mirror ? Draw ray diagram to justify your answer.
7. (a) Predict which of the following elements will form cation and will form anions ?
(i) Na (ii)Al (in) Cl (iv) O
(b) Name two elements that are inert in nature.
8. Give an example of :
(a) A metal that is liquid at room temperature.
(b) A non-metal that is liquid at room temperature.
(c) An inert gas (At. no < 20)
9. Explain the following :
(i) CH3COOH is a weak acid
(ii) Propene undergoes addition reaction
(iii) The gas stoves have inlets for air.
10. Write the molecular, electronic and structural formulae of ethyne.
11. Define the following processes of asexual reproduction.
(i) Spore formation (ii) Regeneration (iii) Multiple fission.
12. Population explosion is not a far reason, infact a number of reasons are behind in the enhancement of people living in a country. Though all the countries are facing this problem, but the problem is very alarming in India. It is threatening the development of the country. Organisms increase their population with the help of reproduction. The rate of birth and death in a given population determines it size. The increase in a population occurs when the birth rate is higher than the death rate. The government find itself unable to manage the facilities for the increased number of population. The Government of India is taking many preventive measures. Family planning is being stressed by the government.
Questions:
(i) Mention any three methods of contraception.
(ii) Suggest three ways which you will take to make rural area people aware about the vitality of
family planning. (Value Based Question)
13. (i) Name the unit of inheritance. What is its functions ?
(ii) How are inherited traits different from acquired traits ? Give example.
14. Show inheritance of two characters over two generations by making a cross between round and yellow seeded plant (RRYY) with wrinkled green seeded plant, (rryy).
15. A student wants to project the image of a candle flame on a screen 48 cm in front of a mirror by keeping the flame at a distance of 12 cm from its pole.
(a) Suggest the type of mirror he should use.
(b) Find the linear magnification of the image produced.
(c) How far is the image from its object ?
(d) Draw the ray diagram to show the image formation in this case.
16. State the laws of refraction of light. If the speed of light in vacuum is 3 x 108 m/s, find the speed of light in a medium of absolute refractive index 1-5.
17. State the laws of refraction of light. If the speed of light in vacuum is 3 x 108 m/s find the absolute refractive index of a medium in which light travels with a speed of 1.4 x 108 m/s.
18. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens of length 10 cm. If the distance of the object from the optical centre of the lens is 20 cm, determine the position, nature and size of the image formed using the lens formula.
19. Elements forming ionic compounds attain noble gas electronic configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this maimer to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also give reason why carbon compounds are generally poor conductors of electricity.
20.(a) Name the parts labeled as A, B, C and D in the diagram given below :
(b) What is pollination ? State its significance.
(c) How does fertilisation occur in flowers ? Name the parts of the flower that develop into (i) seed, and (ii) fruit after fertilisation.
21. What is pollination ? in plants ? How does pollination lead to fertilization ? Explain.
22. Draw a ray diagram in each of the following cases to show the position and nature of image formed
when the object is placed :
(i) Between pole and focus of a concave mirror.
(ii) Between focus and centre of curvature of a concave mirror.
(iii) At the centre of curvature of a concave mirror.
(iv) Between infinity and pole of a convex mirror.
(v) At infinity from a convex mirror.
23. A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect. Draw ray diagram for the :
(i) defect of vision and also
(ii) For its correction. .
24. Eco-club of your school is organising a debate on the topic ‘Nature’s Fury Unleashed by Human’s Greed’ (Uttrakhand Disaster).
(a) List three arguments that you will use to convince the audience that humans are responsible for this disaster.
(b) List any three values that will be inculcated with this debate. (HOTS)
SECTION-B
25. While studying
saponification reaction, a student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations, the correct conclusion would be:
(A) the reaction is exothermic and the reaction mixture is acidic.
(B) the reaction is endothermic and the reaction mixture is acidic.
(C) the reaction is endothermic and the reaction mixture is basic.
(D) the reaction is exothermic and the reaction mixture is basic.
26. In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory :
1. Sodium sulphate
2.Calcium sulphate
3.Magnesium chloride
4. Sodium chloride
5. Calcium chloride
6. Potassium sulphate
Which of the above salts may be dissolved in water to obtain hard water for the experiment ?
(A) 2, 3 and 5
(B) 1, 2 and 5
(C) 1,2,4 and 6
(D) 3 and 5 only
27. A student adds 2 ml of acetic acid to a test-tube containing 2 ml of distilled water. He then shakes the test-tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is:
(A) a clear transparent colourless solution
(B) a clear transparent pink solution
(C) a precipitate settling at the bottom of the test tube
(D) a layer of water over the layer of acetic acid.
28. In the following diagram showing the structure of embryo of a dicot seed, name the parts marked as I, II and III sequentially ?
(A) Plumule, Cotyledon, Radicle (B) Plumule, Radicle, Cotyledon
(C) Cotyledon, Plumule, Radicle (D) Radicle, Plumule, Cotyledon
29. Study the following diagrams showing various stages of binary fission in Amoeba :
The correct sequence of these diagrams should be :
(A) I, IV, III, II, V (B) I, III, IV, II, V
(C) I, II, IV, III, V (D) I, II, III, IV, V
30. The organs are said to be homologous if they have similar :
(A) Structure and dissimilar function
(B) Function and dissimilar structure
(C) Mechanical strength
(D) DNA content
31. A student traces the path of a ray of light passing through a rectangular glass slab and marks the angle of incidence i, angle of refraction r and angle of emergence e, as shown.
32. Study the following diagrams in which the path of a ray of light passing through a glass prism as traced by four students R Q, R and S is shown :
The student who has traced the path correctly is
(A) P (B) Q
(C) R (D) S
33. In the following diagram, the path of a ray of light passing through a glass prism is shown :
In this diagram the angle of incidence, the angle of emergence and the angle of deviation respectively (A) X, R and T (B) Y, Q and Tare:
(C) X, Q and P (D) Y, Q and P
34. Out of the following list of chemicals, select those which are required to study the prescribed four properties of acetic acid in the laboratory litmus solutions ( blue or red), water, alcohol, sodium chloride, sodium hydrogen carbonate, calcium hydroxide solution.
35. A student confirms binary fission process in a unicellular organism after observing a slide under microscope. What he might have observed in that slide to reach to this condition ?
36. Write two precautions to be taken while tracing the path of a ray of light passing through a rectangular glass prism.
Answers
SECTION-A
1. Write the total number of periods in modern periodic table.
Ans. The total number of periods in modern periodic table is seven. [CBSE Marking Scheme, 2015] 1
2. What is a gene ?
Ans. Gene is a part of DNA that encodes the instructions that allow a cell to produce a specific
protein or enzyme. 1
3. The first trophic level in a food chain is always a green plant. Why ?
Ans. Green plants are producers. The first trophic level in a food chain is a producers i.e. those
organisms which produce food by photosynthesis. [CBSE Marking Scheme, 2015] 1
4. Accumulation of harmful chemicals in our bodies can be avoided. Explain how this can be achieved ? (HOTS)
Ans. We should drink plenty of water, eat healthy food, perform exercise and do not take stress to avoid accumulation of harmful chemicals in our body. We should eat more vegetables especially cruciferous vegetables (such as broccoli, cauliflower, etc.) than meat. [CBSE Marking Scheme, 2014] 2
5. In an area A, the leaf material available to beetles was very less. What are the two consequences
seen in the beetles ? (HOTS)
Ans. The consequences are as follows :
(i) They switched to new type of food and entered new niches.
(ii) This lead to arise of diverse variety of beetles as some changes in beetles will take place
to make them adaptable to new niches. 1 + 1
6. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should the position of the object be relative to the mirror ? Draw ray diagram to justify your answer.
Ans.
When the object is located between the focus (F) and the pole (P) of the mirror, the image is formed
behind the mirror; this image is virtual, erect and large. 1
7. (a) Predict which of the following elements will form cation and will form anions ?
(i) Na (ii)Al (in) Cl (iv) O
(b) Name two elements that are inert in nature.
Ans. (a) Cations are Na and A1 (Sodium and Aluminium)
Anions are Cl and O (Chlorine and Oxygen)
(b) Inert elements are He and Ne (Helium and Neon) [CBSE Marking Scheme, 2015] 1 + 1 + 1
8. Give an example of :
(a) A metal that is liquid at room temperature.
(b) A non-metal that is liquid at room temperature.
(c) An inert gas (At. no < 20)
Ans. (a) Mercury
(b) Bromine.
(c) Helium or Neon or Argon [CBSE Marking Scheme, 2015] 1 + 1 + 1
9. Explain the following :
(i) CH3COOH is a weak acid
(ii) Propene undergoes addition reaction
(iii) The gas stoves have inlets for air.
Ans. (i) Due to the incomplete ionization of acetic (CH3COOH) acid.
(ii) CH3 — CH = CH2 undergoes addition reaction because of double bond.
(iii) Sufficient supply of 02 for complete combustion. [CBSE Marking Scheme, 2015] 1 + 1 + 1
10. Write the molecular, electronic and structural formulae of ethyne.
Ans.
11. Define the following processes of asexual reproduction.
(i) Spore formation (ii) Regeneration (iii) Multiple fission.
Ans. (i) Spore formation is a common method of asexual reproduction in many lower forms of life, like bacteria, fungi etc. It occurs mostly during unfavourable conditions such as extreme heat, dryness etc. The spores are asexual reproducing bodies enclosed in a thick walled structure called sporangium. On return of favourable conditions the sporangium wall bursts and the spores are released.
(ii) Regeneration means renewal, restoration, and growth. The process of getting back a full organism from its body parts is called regeneration. Some organism like Hydra, Planaria have the capability to develop a whole new organism from it cut body parts. Regeneration of an organism occurs by the process of growth and development. Regeneration occurs in those organisms which have relatively simple body organization consisting of few specialized cells.
(iii) In multiple fission, the nucleus divides several times simultaneously or successively into a number of daughter nuclei and then the cytoplasm divides into as many cells as there are nuclei, each cell containing a nucleus. It is the common form of asexual reproduction in certain acellular organisms. [CBSE Marking Scheme, 2014] 1 + 1 + 1
12. Population explosion is not a far reason, infact a number of reasons are behind in the enhancement of people living in a country. Though all the countries are facing this problem, but the problem is very alarming in India. It is threatening the development of the country. Organisms increase their population with the help of reproduction. The rate of birth and death in a given population determines it size. The increase in a population occurs when the birth rate is higher than the death rate. The government find itself unable to manage the facilities for the increased number of population. The Government of India is taking many preventive measures. Family planning is being stressed by the government.
Questions:
(i) Mention any three methods of contraception.
(ii) Suggest three ways which you will take to make rural area people aware about the vitality of
family planning. (Value Based Question)
Ans. (i) Three methods of contraception are :
(a) Mechanical Barrier Methods.
(b) Chemical Methods.
(c) Surgical Methods. 1 A
(ii) (a) Discussion of benefits of family planning by people.
(b) Organising seminar.
(c) Making poster.
13. (i) Name the unit of inheritance. What is its functions ?
(ii) How are inherited traits different from acquired traits ? Give example.
Ans. (i) Gene.
It is the carrier of genetic information from one generation to another.
(ii) The traits that are obtained from parents are inherited traits.
e.g., Fused and free ear lobes.
The traits that develop during lifetime of an individual are acquired traits.
Example : Muscular body of a wrestler. [CBSE Marking Scheme, 2012]
14. Show inheritance of two characters over two generations by making a cross between round and yellow seeded plant (RRYY) with wrinkled green seeded plant, (rryy).
Ans. 
15. A student wants to project the image of a candle flame on a screen 48 cm in front of a mirror by keeping the flame at a distance of 12 cm from its pole.
(a) Suggest the type of mirror he should use.
(b) Find the linear magnification of the image produced.
(c) How far is the image from its object ?
(d) Draw the ray diagram to show the image formation in this case.
Ans. 
16. State the laws of refraction of light. If the speed of light in vacuum is 3 x 108 m/s, find the speed of light in a medium of absolute refractive index 1-5.
Ans.
17. State the laws of refraction of light. If the speed of light in vacuum is 3 x 108 m/s find the absolute refractive index of a medium in which light travels with a speed of 1.4 x 108 m/s.
Ans.
–> c = 3 x 108 m/s
v= 1.4 x 108 m/s
–> Absolute refractive index
= Speed of light in vacuum / Speed of light in medium
= 3 x 108 m/s / 1.4 x 108 m/s [CBSE Marking Scheme, 2015] 1/2
18. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens of length 10 cm. If the distance of the object from the optical centre of the lens is 20 cm, determine the position, nature and size of the image formed using the lens formula.
Ans. 
19. Elements forming ionic compounds attain noble gas electronic configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this maimer to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also give reason why carbon compounds are generally poor conductors of electricity.
Ans. The atomic number of carbon is 6. This means that it has 4 electrons in its outermost shell and it needs 4 more electrons to attain noble gas electronic configuration. It cannot form C4+ cation, as the removal of 4 valence electrons requires a huge amount of energy. The cation formed has 6 protons and 2 electrons. This makes it highly unstable. Carbon cannot form C4- anion, as its nucleus with 6 pretons cannot hold 10 electrons. Thus, carbon achieves noble gas electronic configuration by sharing its 4 electrons with other elements, e., it forms covalent compounds. In ionic compounds, ionic bonds are formed; while in carbon compounds, covalent bonds are formed.
Because carbon compounds are covalent in nature, they are bad conductors of electricity; they lack free electrons. 4
20.(a) Name the parts labeled as A, B, C and D in the diagram given below :
(b) What is pollination ? State its significance.
(c) How does fertilisation occur in flowers ? Name the parts of the flower that develop into (i) seed, and (ii) fruit after fertilisation.
Ans. 
In the given figure,
A represents the pollen grain.
B represents the pollen tube.
C represents the ovary.
(b) The transfer of pollen grains from the anther to the stigma of a flower is known as pollination.
Significance of pollination:
(i) It is a significant event because it precedes fertilisation.
(ii) It brings the male and female gametes closer for the process of fertilisation.
(iii) Cross-pollination introduces variations in plants because of the mixing of different genes. These variations further increase the adaptability of plants towards the environment or surroundings.
(c) Double fertilisation is a characteristic feature of flowering plants. In this process, out of the two sperm nuclei, one sperm nuclei fuses with the egg nuclei to form an embryo (process is called syngamy) and another fuses with the polar nuclei to form an endosperm (process is called triple fusion) .Because two kinds of fusion—syngamy and triple fusion—take place, the process is known as double fertilisation. After fertilisation,
(i) the ovule develops into a seed.
(ii) the ovary develops into a fruit.
21. What is pollination ? in plants ? How does pollination lead to fertilization ? Explain.
Ans. The transfer of pollens from anther to the stigma of a flower is called pollination.
The transfer is accomplished by an external agency such as wind (anemophily), water (hydrophily), insects (entomophily), birds (ornithophily), bats (chiropterophily), etc. Both wind and water are abiotic agencies while insects, birds, bats etc. are biotic agencies of pollination.
After falling on stigma, the pollen grain absorbs water and nutrients. It produces a tube called pollen tube. Pollen tube grows through style and reaches the ovary. Its tip contains a tube nucleus and two male gametes or sperm cells. The advancing pollen tube enters an ovule, generally through micropyle and reaches the interior of the embryo sac. Here the tube bursts to release its two male gametes. One male gamete fuses with egg to form zygote and the second male gamete fuses with binucleate central cells which forms endosperm.
22. Draw a ray diagram in each of the following cases to show the position and nature of image formed
when the object is placed :
(i) Between pole and focus of a concave mirror.
(ii) Between focus and centre of curvature of a concave mirror.
(iii) At the centre of curvature of a concave mirror.
(iv) Between infinity and pole of a convex mirror.
(v) At infinity from a convex mirror.
Ans.
23. A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect. Draw ray diagram for the :
(i) defect of vision and also
(ii) For its correction.
Ans. Myopia on short-sightedness: Inability of an eye in viewing long distance objects. The image in this case falls before the retina. For every myopic eye, there exists a far point beyond which clear image cannot be seen.
The short-sightedness is corrected by using a concave lens which diverges and shifts the image to the retina.
24. Eco-club of your school is organising a debate on the topic ‘Nature’s Fury Unleashed by Human’s Greed’ (Uttrakhand Disaster).
(a) List three arguments that you will use to convince the audience that humans are responsible for this disaster.
(b) List any three values that will be inculcated with this debate. (HOTS)
Ans. (a) Mining, unnecessary use of resources, cutting of trees, building, concrete jungle. 3
(b) To protect and improve the natural environment, social awareness, environmental conservation, eco-friendly approach, value for life. [CBSE Marking Scheme, 2015] 2
SECTION-B
25. While studying
saponification reaction, a student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations, the correct conclusion would be:
(A) the reaction is exothermic and the reaction mixture is acidic.
(B) the reaction is endothermic and the reaction mixture is acidic.
(C) the reaction is endothermic and the reaction mixture is basic.
(D) the reaction is exothermic and the reaction mixture is basic.
Ans. (D) Saponification reaction is a highly exothermic reaction. The reaction mixture of this reaction is
basic in nature and hence, this will turn red litmus blue.
26. In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory :
1. Sodium sulphate
2.Calcium sulphate
3.Magnesium chloride
4. Sodium chloride
5. Calcium chloride
6. Potassium sulphate
Which of the above salts may be dissolved in water to obtain hard water for the experiment ?
(A) 2, 3 and 5
(B) 1, 2 and 5
(C) 1,2,4 and 6
(D) 3 and 5 only
Ans. (A) Water containing calcium and magnesium salts is known as hard water. Among the given salts, calcium sulphate, magnesium chloride and calcium chloride can be dissolved in water to obtain hard water.
27. A student adds 2 ml of acetic acid to a test-tube containing 2 ml of distilled water. He then shakes the test-tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is:
(A) a clear transparent colourless solution
(B) a clear transparent pink solution
(C) a precipitate settling at the bottom of the test tube
(D) a layer of water over the layer of acetic acid.
Ans. (A) a clear transparent colourless solution.
28. In the following diagram showing the structure of embryo of a dicot seed, name the parts marked as I, II and III sequentially ?
(A) Plumule, Cotyledon, Radicle (B) Plumule, Radicle, Cotyledon
(C) Cotyledon, Plumule, Radicle (D) Radicle, Plumule, Cotyledon
Ans. (A) In the given figure, I represents the plumule, II represents the cotyledon and III represents the radicle.
29. Study the following diagrams showing various stages of binary fission in Amoeba :
The correct sequence of these diagrams should be :
(A) I, IV, III, II, V (B) I, III, IV, II, V
(C) I, II, IV, III, V (D) I, II, III, IV, V
Ans. (B) During binary fission, the nucleus of the parent cell elongates and divides initially. A constriction starts appearing on the cell membrane. It starts widening and finally divides the parent cell into two almost equal halves (daughter cells). The daughter cells are identical to the parent cell. 1
30. The organs are said to be homologous if they have similar :
(A) Structure and dissimilar function
(B) Function and dissimilar structure
(C) Mechanical strength
(D) DNA content
Ans. (A) Structure and dissimilar function.
31. A student traces the path of a ray of light passing through a rectangular glass slab and marks the angle of incidence i, angle of refraction r and angle of emergence e, as shown.
Ans. (C) Angle of incidence, angle of refraction and angle of emergence, all are measured from the normal to the surface. Therefore, only angle of refraction, r is marked correctly.
32. Study the following diagrams in which the path of a ray of light passing through a glass prism as traced by four students R Q, R and S is shown :
The student who has traced the path correctly is
(A) P (B) Q
(C) R (D) S
Ans. (B) Student Q has traced the path correctly. When light is travelling from a rarer medium to a denser medium, it bends towards the normal of the surface, while the light from a denser medium to a rarer medium bends away from the normal of the surface
33. In the following diagram, the path of a ray of light passing through a glass prism is shown :
In this diagram the angle of incidence, the angle of emergence and the angle of deviation respectively (A) X, R and T (B) Y, Q and Tare:
(C) X, Q and P (D) Y, Q and P
Ans. (D) The angle made by the incident ray with the normal of the first face of the prism is called incident angle, which is angle Y here. The angle made by the emergent ray with the normal of the surface when it comes out from the prism after refraction is called emergent angle, which is angle Q here. The angle between the incident ray and the emergent ray is called angle of deviation, which is angle P here.
34. Out of the following list of chemicals, select those which are required to study the prescribed four properties of acetic acid in the laboratory litmus solutions ( blue or red), water, alcohol, sodium chloride, sodium hydrogen carbonate, calcium hydroxide solution.
Ans. Blue litmus solution, water, sodium hydrogen carbonate and calcium hydroxide solution
35. A student confirms binary fission process in a unicellular organism after observing a slide under microscope. What he might have observed in that slide to reach to this condition ?
Ans. (i) An organism having elongated and constricted nucleus.
(ii) An organism having two nuclei with constriction in between. [CBSE Marking Scheme, 2015] 1 + 1
36. Write two precautions to be taken while tracing the path of a ray of light passing through a rectangular glass prism.
Ans. The glass slab should be perfectly rectangular with all its faces smooth.
b. While fixing the pins PI and P2 or the pins P3 and P4, care should be taken to maintain a distance of about 5 cm between the two pins. This would help in tracing the direction of incident ray and that of emergent ray with greater accuracy. 1 + 1
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