DWPS
BHARAT
01
Class 10 - Science
Time Allowed: 3 hours Maximum Marks: 80
Section A
1. While demonstrating acid-base reactions, Ms. Rajnish, a science teacher added sodium oxide to HCI until it was [1]
in excess. Which of the following graphs correctly represents the change in pH?
a) b)
c) d)
2. Which of the following has an electrovalent bond(s)? [1]
A. CaF
B. NaCl
C. MgO
D. CO2
a) A and C b) A, B and C
c) All of these d) C and D
3. The kidneys in human beings are a part of the system for [1]
a) respiration b) excretion
c) nutrition d) transportation
4. The main function of abscisic acid in plants is to [1]
a) promote cell division b) increase the length of cells
c) promote growth of stem d) inhibit growth
5. In a flower, the parts that produce male and female gametes (germ cells) are [1]
a) stamen and style b) filament and stigma
c) anther and ovary d) stamen and anther
6. Select the correct statement among the following. [1]
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i. Human female possesses homomorphic sex chromosomes.
ii. Males possess homogametic sex chromosomes in humans.
iii. Human females possess heterogametic sex chromosomes.
iv. Human male possesses homomorphic sex chromosomes.
a) Statement (iii) is correct. b) Statement (i) is correct.
c) Statement (ii) is correct. d) Statement (iv) is correct.
7. The image distance from the eye lens in the normal eye when we increase the distance of an object from the eye [1]
a) depends on the size of the eyeball b) increases
c) remains unchanged d) decreases
8. A battery of 9V is connected in series with resistors of 0.2 Ω , 0.3 Ω , 0.4 Ω , 0.5 Ω , and 12 Ω . How much current [1]
would flow through the 12 resistors?
a) 0.2 amp b) 0.61 amp
c) 0.67 amp d) 0.66 amp
9. Consider the following combinations of resistors: [1]
The combinations having equivalent resistance 1Ω is/are:
a) I and II b) I and IV
c) I, II and III d) Only IV
10. Refer to the given pie chart regarding contribution of different greenhouse gases and select the incorrect [1]
statement regarding it.
a) S is used in aerosol cans, jet fuel, air b) Q is also produced by incomplete
conditioners and refrigerators. decomposition mostly by anaerobic
methanogens.
c) R are synthetic gaseous compounds of d) Excessive use of fossil fuel is adding more
carbon and halogen. P to atmosphere.
.
11. Assertion (A): The metal sulphides and carbonates are converted to metal oxides in the process of extraction of [1]
metal from them.
Reason (R): It is because it is easier to obtain metal from its oxide.
a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
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explanation of A. correct explanation of A.
c) A is true but R is false. d) A is false but R is true.
12. Assertion (A) : Dark phase is independent of light, hence called light independent phase. [1]
Reason (R) : Dark phase takes place at night.
a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of A. correct explanation of A.
c) A is true but R is false. d) A is false but R is true.
13. Assertion (A): If a spherical mirror is dipped in water, its focal length remains unchanged. [1]
Reason (R): A laser light is focused by a converging lens. There will be a significant chromatic aberration.
a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of A. correct explanation of A.
c) A is true but R is false. d) A is false but R is true.
14. Assertion (A): The direction of force is given by Flemings left hand rule. [1]
Reason (R): A magnetic field exert a force on a moving charge in the same direction as the direction of field
itself.
a) Both A and R are true and R is the correct b) Both A and R are true but R is not the
explanation of A. correct explanation of A.
c) A is true but R is false. d) A is false but R is true.
.
15. What happens in the test tube shown here? [1]
a) H2O will produce b) SO2 will produce
c) No reaction d) FeO will produce
16. On putting few drops of an unknown liquid on the pH strip as shown here, the colour of pH strip changed to [1]
violet.The liquid taken is likely to be :
a) dilute acetic acid b) dilute sodium hydroxide
c) water d) dilute hydrochloric acid
17. The electron dot structure of chlorine molecule is: [1]
a) b)
c) d)
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18. In which of the following, binary fission observed: [1]
a) A b) D
c) C d) B
19. A student traces the path of a ray of light passing through a rectangular glass slab for three different values of [1]
angle of incidence (i) namely 30o, 45o, 60o. He produces the incident ray and measures the perpendicular
distance, l, between the produced incident ray and the emergent ray.
He will observe that
a) 'l' keeps on increasing with increase in angle b) 'l' keeps on decreasing with increase in
of incidence. angle of incidence.
c) 'l' remains the same for all three angles of d) 'l' is maximum for ∠ i = 45o and is less than
incidence.
this value both for ∠ i = 30oand for ∠ i=
60o.
20. The resultant magnetic field at point P situated midway between two parallel wires (placed horizontally each [1]
carrying a steady current I is
a) in the same direction as the current in the b) zero
wires.
c) in the vertically upward direction. d) in the vertically downward direction.
Section B
21. Give the name and formula of two [2]
i. strong monobasic acids
ii. two weak dibasic acids
OR
Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they
were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.
22. i. What are metals? Name five metals. [2]
ii. Name a metal which is so soft that it can be cut with a knife.
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iii. Name the metal which is the best conductor of heat and electricity.
iv. What happens when a metal reacts with dilute hydrochloric acid? Explain with the help of an example.
23. What is gland? Name the two types of glands. [2]
24. Velocity of light in diamond is 1.2 × 108 ms-1 and in vacuum, it is 3 × 108 ms-1, what is refractive index of [2]
diamond ?
25. We are able to see everything with one eye, then why do we have two eyes ? [2]
OR
Which defect of the eye is known as far-sightedness? When does this defect arise? State two reasons. How is this
defect corrected?
26. a. What is an ecosystem? [2]
b. List any two natural ecosystems.
c. We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Why?
27. Identify the type of reaction in the following [3]
a. ZnCO3 + 2HCl(aq) ⟶ ZnCl2(aq) + H2CO3(aq)
b. 2NaBr(aq) + Cl2(g) ⟶ 2NaCl(aq) + Br2(aq)
heat
c. 2CuO(s) −−→ 2Cu(s) + O2(g)
28. A portion of destarched leaf of a potted plant was covered with a black strip of paper. The plant was exposed to [3]
sunlight for six hours and then tested for starch. What will be the observation?
OR
In each of the following situations what happens to the rate of photosynthesis?
i. Cloudy days
ii. No rainfall in the area
iii. Good manuring in the area
iv. Stomata get blocked due to dust
29. What are Chromosomes? Explain how stability of the DNA of the species is ensured in sexually reproducing [3]
organisms.
30. Outline a project which aims to find the dominant coat colour in dogs. [3]
31. Distinguish between a convex lens and a concave lens. [3]
OR
A student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle
flame at a distance of 20 cm from its pole.
i. Which type of mirror should the student use?
ii. Find the magnificent of the image produced.
iii. Find the distance between the object and its image.
32. V - I graph for two conducting wires A and B are as shown. If both wires are of the same length and same [3]
diameter, which of the two is made of a material of high resistivity? Give reasons to justify your answer.
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33. A circular metallic loop is kept above the wire AB as shown below: [3]
What is the direction of induced current produced in the loop, if the current flowing in the straight wire
i. is steady, i.e. does not vary?
ii. is increasing in magnitude?
34. i. What are hydrocarbons? Give examples. [5]
ii. Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
iii. What is functional group? Give examples of four different functional groups.
OR
i. Why is acidified water considered to be a good conductor of electricity?
ii. Write a chemical equation showing the ionic products formed ondissolving potassium hydroxide in water.
iii. Care must be taken while diluting concentrated nitric acid with water. Why?
35. Given below is a labelled diagram of the human brain. [5]
Using the given diagram, answer the following questions:
i. Which part of the brain controls reflex movements of the head, neck, and trunk?
ii. Name the part of the human brain which contains a vital centre for controlling blood pressure.
iii. Which part of the hindbrain regulates respiration?
iv. How is the brain protected from injuries and shock?
v. Which part of the human brain is the main thinking region?
OR
Given below is a well-labelled diagram showing synapse between the two neurons.
Using the given diagram, answer the following questions:
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i. What is the sequence in which nerve impulse travels?
ii. How synapse between two neurons acts as a one-way valve?
iii. Which chemical substance is released when an electrical impulse coming from the receptor reaches the end of the
axon of a sensory neuron?
iv. How a neurotransmitter starts an electrical impulse in the next neuron?
v. Which part of the neuron has a synaptic knob?
36. A bulb is rated 40 W; 220 V. Find the current drawn by it, when it is connected to a 220 V supply. Also find its [5]
resistance. If the given bulb is replaced by a bulb of rating 25 W; 220 V, will there be any change in the value of
current and resistance? Justify your answer and determine the change.
OR
Derive the relation , when resistors are joined in parallel.
1 1 1 1
= + +
R R1 R2 R3
Section E
37. Read the following text carefully and answer the questions that follow: [4]
Non-metals are highly electronegative in nature. They have a tendency to gain electrons in their valence shell to
achieve nearest noble gas configuration. Thus, they form anions and act as good oxidising agents.
− n−
X + ne → X
(non−metal atom) (anion)
They react with air or oxygen on heating to form oxides which react with water to form acids. Thus, non-metal
oxides are acidic in nature. Non-metals do not react with dilute acids at all. This is because they are
electronegative and therefore, cannot displace hydrogen from acids but they form covalent hydrides when heated
with hydrogen.
i. What happens when sulphur trioxide reacts with water? (1)
ii. Why non-metals are electronegative in nature? (1)
iii. Why non-metals generally act as oxidising agents? (2)
OR
Why do non-metals not react with dilute acids? (2)
38. Read the following text carefully and answer the questions that follow: [4]
We have seen that the different parts of our body have specific functions. Our mouth waters when we see the
food we like without our meaning to. Our heart's beat without our thinking about it. In fact, we cannot control
these actions easily by thinking about them even if we wanted to. So, in between the simple reflex actions like
change in the size of the pupil, and the thought out actions such as moving a chair, there is another set of muscle
movements over which we do not have any thinking control. Many of these involuntary actions are controlled by
the mid-brain and hind-brain. All these involuntary actions including blood pressure, salivation and vomiting are
controlled by the medulla in the hind-brain. Think about activities like walking in a straight line, riding a
bicycle, picking up a pencil. These are possible due to a part of the hind-brain called the cerebellum. It is
responsible for the precision of voluntary actions and maintaining the posture and balance of the body. Imagine
what would happen if each of these events failed to take place if we were not thinking about it.
i. Identify the part of the nervous system which controls the reflex action. (1)
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ii. Does reflex action involve all parts of the voluntary nervous system? (1)
iii. Identify the part of the autonomic nervous system which controls involuntary actions. (1)
OR
Beating of heart muscles, which type of action is this? Out of voluntary and involuntary action which is
slower? (2)
39. Read the following text carefully and answer the questions that follow: [4]
Atmospheric refraction is the phenomenon of bending of light on passing through earth’s atmosphere. As we
move above the surface of earth, density of air goes on decreasing. Local conditions like temperature etc. also
affect the optical density of earth’s atmosphere. On account of atmospheric refraction, stars seen appear higher
than they actual are; advanced sunrise; delayed sunset, oval appearance of the sun at sunrise and sunset; stars
twinkle, planets do not.
i. How does atmospheric refraction affect the apparent length of the day? (1)
ii. Why does Sun appear slightly oval shaped at morning and evening? (1)
iii. Why do the stars twinkle but planets don't? (2)
OR
What color does the sky appear in the absence of an atmosphere? (2)
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