SITA GRAMMAR SCHOOL

PREBOARD-1 SET-B
Class 10 - Science
Time Allowed: 3 hours Maximum Marks: 80

General Instructions:

1. This question paper consists of 39 questions in 5 sections.

2. All questions are compulsory. However, an internal choice is provided in some questions. A student is expected to

attempt only one of these questions.

3. Section A consists of 20 objective-type questions carrying 1 mark each.

4. Section B consists of 6 Very Short questions carrying 02 marks each. Answers to these questions should be in the

range of 30 to 50 words.

5. Section C consists of 7 Short Answer type questions carrying 03 marks each. Answers to these questions should
be in the range of 50 to 80 words.

6. Section D consists of 3 Long Answer type questions carrying 05 marks each. Answers to these questions should

be in the range of 80 to 120 words.

7. Section E consists of 3 source-based/case-based units of assessment of 04 marks each with sub-parts.

Section A
1. Which type of chemical reaction is shown in the given image? [1]

a) Redox reaction b) Combination reaction

c) Decomposition reaction d) Displacement reaction

2. Consider the following Chemical equation: [1]
a Al2O3 + b HCl → c AlCl3 + d H2O

In order to balance this chemical equation, the values of a, b, c and d must be

a) 2, 6, 2 and 3 b) 1, 6, 3 and 2

c) 1, 6, 2 and 3 d) 2, 6, 3 and 2
3. Which of the given statement is correct: [1]
Statement A: All metals form basic oxides.
Statement B: Few non-metals form neutral oxides.

a) Both the statements A and B are false. b) Statement B is true. Statement A is false.

c) Statement A is true. Statement B is false. d) Both the statements A and B are true.
4. Which of the following statements are false about soaps and detergents? [1]
i. Soaps are water soluble while detergents are not.

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 ii. Soaps are non-biodegradable while detergents are biodegradable.
iii. Hardness of water is due to presence of Ca and Mg salts which form scum with soap.
iv. The polar group in soaps is -COONa.

a) (iii) and (iv) only b) (i) and (ii) only

c) (i), (ii) and (iv) only d) (i), (ii) and (iii) only
5. What happens when ammonia reacts with hydrogen chloride? NH3 + HCl → ? [1]

a) Both H2 and NH4Cl b) H2 gas is evolved

c) NH4Cl is formed d) Cl2 gas is evolved.

6. Consider the following compounds: [1]

I. HCl
II. C2H5OH

III. C6H12O6
IV. H2SO4

Which of these compounds do not conduct electricity in solution?

a) III and IV b) I and IV

c) II and III d) I and II

7. An organic compound X has the molecular formula C2H6O. Upon reaction with alkaline KMnO4 it gets oxidised [1]
to compound Y. Which of the following reagents can be used to distinguish between compounds X and Y?

a) Sodium hydroxide b) All of these

c) Sodium metal d) Sodium carbonate

8. Which is the correct sequence of the components of a reflex arc? [1]

a) Receptors → Muscles → Sensory neuron b) Receptors → Motor neuron → Spinal cord

→ Motor neuron → Spinal cord → Sensory neuron → Muscle

c) Receptors → Sensory neuron → Spinal d) Receptors → Spinal cord → Sensory

cord → Motor neuron → Muscle neuron → Motor neuron → Muscle
9. Which of the following is not a character selected by Mendel? [1]
A. Flower shape
B. Pod colour
C. Pod position
D. Branch length

a) A and C b) A, B and D

c) A and D d) B and C
10. In human beings, fertilization of ovum takes place in: [1]

a) Fallopian tubes b) Ovary

c) Uterus d) Vagina
11. In an experiment with pea plants, a pure tall plant (TT) is crossed with a pure short plant (tt). The ratio of pure [1]

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 tall plant to pure short plants in F2 generation will be

a) 1 : 3 b) 3 : 1

c) 2 : 1 d) 1 : 1
12. Two pea plants one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce F1 [1]
progeny that have round, yellow (RrYy) seeds. When F1 plants are selfed, the F2 progeny will have new

combination of characters. Choose the new combination from the following

i. Round, yellow
ii. Round, green
iii. Wrinkled, yellow
iv. Wrinkled, green

a) (i) and (iv) b) (i) and (iii)

c) (ii) and (iii) d) (i) and (ii)

13. When a coil carries current in an anti clockwise direction what pole does it create? [1]

a) South pole b) Zero pole

c) North pole d) both South pole and North pole

14. For the given data showing object distance and focal length of three concave mirrors, answer the following [1]
question :

S. No. object distance (cm) focal length (cm)

1 30 20

2 10 15

3 20 10

Which mirror is being used as a make-up mirror?

a) Case II b) Case I

c) Case III d) Case I and III

15. The decomposers in an ecosystem: [1]

a) Do not breakdown organic compounds b) Convert inorganic material to simpler forms

c) Convert organic material to inorganic forms d) Convert inorganic materials into organic
compounds
16. The table below lists some information about the trophic levels of a food chain. [1]

Energy in the
Trophic Number of
trophic level
level organisms
(arbitrary units)

P 100 10,000

Q 1 100

R 1000 100,000

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 S 10 1000

Which of the following food chains is correct?

a) P → 0 → R → S b) R → P → S → Q

c) P → S → Q → R d) R → Q → S → P
17. Assertion (A): Pungent smelling gas is produced when sulphur burns in air. [1]
Reason (R): Sulphur trioxide is formed on reaction of sulphur with oxygen.

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.

18. Assertion (A): Condom protects a person from the sexually transmitted diseases. [1]
Reason (R): Condom prevents the sperms from meeting the ovum by acting as a barrier.

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.

19. Assertion (A): A compass is kept near a wire carrying current gets deflected. [1]
Reason (R): Electric current is capable of producing a magnetic effect.

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.

20. Assertion (A): In an ecosystem, the function of producers is to convert organic compounds into inorganic [1]
compounds.
Reason (R): Green plants, the producers, transduce solar energy.

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.

Section B
21. i. A liquid compound X is made up of carbon, oxygen and hydrogen elements. It has 8 covalent bonds. It [2]
releases hydrogen gas upon reaction with alkali metal. What is the chemical compound?
ii. Write formula of two homologs of the compound X.
22. How is the process of pollination different from fertilisation? [2]
23. A plant with violet flowers (VV) was crossed with a plant with white flowers (vv). [2]
a. What colour of flowers was obtained in the plants of F1 generation and why?

b. Write the percentage of plants with white flowers in F2 generation plants, if F1 plants were self-pollinated.

Give reason why this trait was not expressed in F1 generation.

c. In what ratio did we get the plants with (VV) and (Vv) gene combination in the F2 generation?

OR
Guinea pig having black colour when crossed with guinea pig having same colour produced 80 offspring, out of
which 60 were black and 20 were white. Now find out:

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 i. What is the possible genotype of the guinea pigs?
ii. Which trait is dominant and which trait is recessive?
iii. What is this cross called as and what is its phenotypic ratio?
24. Draw ray diagrams for the following cases when a ray of light: [2]
i. passing through centre of curvature of a concave mirror is incident on it.
ii. parallel to principal axis is incident on convex mirror.
iii. is passing through focus of a concave mirror incident on it.
25. The following organisms form a food chain. Insects, hawk, grass, snake, frog. Arrange them in proper sequence [2]
to form a food chain? Which of these will have the highest concentration of non-biodegradable chemicals?
Name the phenomenon associated with it?
OR
Mention the amount of solar energy captured by the green plants out of the total energy that reaches on the earth from
the Sun and mention the percentage of energy, which is transferred from one trophic level to next higher one.

26. The refractive indices of glass and water with respect to air are 3

2
and 4

3
respectively. If speed of light in glass is [2]

2 × 108 m/s, find the speed of light in water.

Section C
27. What is reflex action? Explain the mechanism of reflex action with a suitable example. [3]
28. P, Q and R are 3 elements which undergo chemical reactions according to the following equations: [3]
a. P2O3 + 2Q → Q2O3 + 2P

b. 3RSO4 + 2Q → Q2(SO4)3 + 3R

c. 3RO + 2P → P2O3 + 3R
Answer the following questions:
i. Which element is most reactive?
ii. Which element is least reactive?
iii. State the type of reaction listed above.
OR
In a chemistry laboratory, students were instructed to set up three experiments, details of which are given below:

Experiment
Set up details
No.

1. 2 iron nails in a cork capped test tube + Tap water immersing the nails +

2. 2 iron nails in a cork capped test tube + Boiled water immersing the nails + Oil on top of water layer.

2 iron nails In a cork capped test tube + Cotton wool on top of the iron nails + Granules of calcium
3.
chloride on cotton wool.

Indicate the changes observed in the nails kept in all the three setups, with reasons.

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29. The atomic number of an element is 20. Write its electronic configuration. State whether this element is a metal [3]
or a non-metal. What is its valency? Write the name and formula of the compound which this element forms
with chlorine.
30. A man with blood group A married a person with blood group O. Their daughter has blood group O. Is this [3]
information enough to tell you which of the blood group trait A or O is dominant. Why or why not?
31. "A concave mirror of focal length f can form a magnified, erect as well as an inverted image of an object placed [3]
in front of it." Justify this statement stating the position of object with respect to the mirror in each case for
obtaining these images.
32. i. State the direction of magnetic field in the following case. [3]

ii. How does the strength of magnetic field due to a current-carrying conductor depend upon
a. distance from the conductor?
b. current flowing through the conductor?
33. Sudha finds out that the sharp image of window pane of her science laboratory is formed at a distance of 15 cm [3]
from the lens. She now tries to focus the building visible of her outside the window instead of the window pane
without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building?
What is the approximate focal length of this lens?
Section D
34. Write the chemical formula and name of the compound which is the active ingredient of all alcoholic drinks. List [5]
its two uses. Write the chemical equation and name of the product formed when this compound reacts with -
a. sodium metal
b. hot concentrated sulphuric acid
OR
i. Name a commercially important carbon compound having functional group -OH and write its molecular formula.
ii. Write chemical equation to show its reaction with
1. Ethanoic acid in the presence of an acid catalyst
2. Acidified potassium dichromate
iii. Also write the name of the product formed in each case.
iv. What will happen if we add NaOH in one of the products formed in question ii. part 1.

35. i. Use of a condom is beneficial for both the sexes involved in a sexual act. Justify this statement giving two [5]
reasons.
ii. How do oral contraceptive help in avoiding pregnancies?
iii. What is sex selective abortion? How does it affect a healthy society? (State any one consequence)
OR
Why do we call pituitary gland as the master gland? Where is it located and what are its functions?
36. A concave mirror of focal length 60 cm is used to form an image of an object of length 9 cm kept at a distance of [5]
30 cm from it. Use mirror formula to determine the nature, position and length of the image formed. Also draw
labelled ray diagram to show the image formation in the above case.

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 OR
The variation of image distance (v) with object distance (u) for a convex lens is given in the following observation
table. Analyse it and answer the questions that follow:

S. No. Object distance (u) cm Image distance (v) cm

1 -150 +30

2 -75 +37.5

3 -50 +50

4 -37.5 +75

5 -30 +150

6 -15 +37.5

i. Without calculation, find the focal length of the convex lens. Justify your answer.
ii. Which observation is not correct? Why? Draw ray diagram to find the position of the image formed for this
position of the object.
iii. Find the approximate value of magnification for u = -30 cm.
Section E
37. Read the following text carefully and answer the questions that follow: [4]
Those reactions in which two compounds react by an exchange of ions to form two new compounds are called
double displacement reactions. A double displacement reaction usually occurs in solution and one of the
products, being insoluble, precipitate out (separates as a solid). Any reaction in which an insoluble solid (called
precipitate) is formed that separates from the solution is called a precipitation reaction. The reaction in which
acid or acidic oxide reacts with base or basic oxide to form salt and water is called neutralisation reaction.
For example, 2NaOH + H2SO4 ⟶ Na2SO4 + H2O

i. When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of
copper sulphide is obtained and the sulphuric acid so formed remains in the solution. Mention the type of
reaction. (1)
ii. Balance the following chemical reaction. (1)
Pb(NO3)2(aq) + KI(aq) ⟶ PbI2(s) + KNO3(aq)
iii. Barium chloride in reaction with ammonium sulphate forms barium sulphate and ammonium chloride.
Which type of chemical reaction represents in this reaction? Also write their physical states. (2)
OR
Identify A in the following reaction, also mention the type of chemical reaction. (2)
AlCl3(aq) + 3NH4OH(aq) ⟶ A + 3NH4Cl(aq)

38. Read the following text carefully and answer the questions that follow: [4]
In animals, control and coordination are provided by nervous and muscular tissues. Touching a hot object is an
urgent and dangerous situation for us. We need to detect it and respond to it. How do we detect that we are
touching a hot object? All information from our environment is detected by the specialised tips of some nerve
cells. These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so
on. So gustatory receptors will detect taste while olfactory receptors will detect the smell. This information,
acquired at the end of the dendritic tip of a nerve cell, see figure, sets off a chemical reaction that creates an

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 electrical impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end.

i. Name the largest cell present in the body. (1)

ii. What is an axon? (1)
iii. Name one gustatory receptor and one olfactory receptor present in a human beings. (2)
OR
Name the following parts of a neuron: (2)
a. Where information is acquired.
b. Through which information travels as an electrical impulse.
39. Read the following text carefully and answer the questions that follow: [4]
A magnetic field is described by drawing the magnetic field lines. When a small north magnetic pole is placed in
the magnetic field created by a magnet, it will experience a force. And if the north pole is free, it will move
under the influence of the magnetic field. The path traced by a north magnetic pole free to move under the
influence of a magnetic field is called a magnetic field line.

Since the direction of the magnetic field line is the direction of the force on a north pole, so the magnetic field
lines always begin from the N-pole of a magnet and end on the S-pole of the magnet. Inside the magnet,
however, the direction of magnetic field lines is from the S-pole of the magnet to the N-pole of the magnet.
Thus, the magnetic field lines are closed curves. When a small compass is moved along a magnetic field line, the
compass needle always sets itself along the line tangential to it. So, a line drawn from the south pole of the
compass needle to its north pole indicates the direction of the magnetic field at that point.
i. The figure shows the magnetic field lines in a magnetic field. A, B., and C are three points in this field. At
what point is the magnetic field strength? (1)

ii. Do the magnetic field lines intersect? if not why? (1)

iii. A strong bar magnet is placed vertically above a horizontal wooden board. What would be the magnetic lines
of force? (2)

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OR
Draw the pattern of magnetic field lines for a bar magnet. (2)

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