Science · Sample Paper 2

General instructions

Section A · Objective

1. Question 11 mark

   The process in which a solid changes directly into vapour without becoming a liquid is called

   1. A.evaporation
   2. B.sublimation
   3. C.condensation
   4. D.fusion
2. Question 21 mark

   The latent heat of fusion is the heat needed to

   1. A.raise the temperature of 1 kg of a solid by 1 °C
   2. B.change 1 kg of a solid into a liquid at its melting point
   3. C.change 1 kg of a liquid into vapour
   4. D.boil a liquid
3. Question 31 mark

   Which of the following is a compound?

   1. A.Air
   2. B.Brass
   3. C.Water
   4. D.Sea water
4. Question 41 mark

   The technique used to separate the coloured components of black ink is

   1. A.distillation
   2. B.chromatography
   3. C.sublimation
   4. D.filtration
5. Question 51 mark

   The atomicity of ozone (O₃) is

   1. A.1
   2. B.2
   3. C.3
   4. D.4
6. Question 61 mark

   The mass of 0.5 mole of water molecules is (H = 1 u, O = 16 u)

   1. A.18 g
   2. B.9 g
   3. C.36 g
   4. D.4.5 g
7. Question 71 mark

   The particle discovered by J.J. Thomson is the

   1. A.proton
   2. B.neutron
   3. C.electron
   4. D.nucleus
8. Question 81 mark

   An atom has 17 protons and 18 neutrons. Its mass number is

   1. A.17
   2. B.18
   3. C.35
   4. D.1
9. Question 91 mark

   Which organelle is called the 'suicide bag' of the cell?

   1. A.Golgi apparatus
   2. B.Lysosome
   3. C.Plastid
   4. D.Vacuole
10. Question 101 mark

    The cell wall of plant cells is mainly made of

    1. A.protein
    2. B.cellulose
    3. C.lipid
    4. D.starch
11. Question 111 mark

    Which plant tissue is responsible for growth in length at the tips of roots and stems?

    1. A.Lateral meristem
    2. B.Apical meristem
    3. C.Intercalary meristem
    4. D.Permanent tissue
12. Question 121 mark

    The slope of a distance–time graph gives

    1. A.acceleration
    2. B.speed
    3. C.displacement
    4. D.force
13. Question 131 mark

    A passenger in a bus falls backward when the bus starts suddenly. This is due to

    1. A.inertia of motion
    2. B.inertia of rest
    3. C.friction
    4. D.gravity
14. Question 141 mark

    If the mass of a body is doubled and the distance from another body is also doubled, the gravitational force between them

    1. A.is doubled
    2. B.is halved
    3. C.becomes four times
    4. D.stays the same
15. Question 151 mark

    1 kilowatt hour is equal to

    1. A.3.6 × 10⁶ J
    2. B.3.6 × 10³ J
    3. C.1000 J
    4. D.3600 J
16. Question 161 mark

    The audible range of frequencies for human beings is

    1. A.2 Hz to 20 Hz
    2. B.20 Hz to 20 000 Hz
    3. C.20 kHz to 200 kHz
    4. D.above 20 kHz
17. Question 171 mark

    Assertion (A): A solution of sugar in water does not scatter a beam of light.

    Reason (R): The particles in a true solution are smaller than 1 nm in diameter.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
18. Question 181 mark

    Assertion (A): Xylem and phloem are called complex tissues.

    Reason (R): They are made of more than one type of cell working together.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
19. Question 191 mark

    Assertion (A): When a person carries a suitcase and walks on a level road, the work done by the person against gravity is zero.

    Reason (R): Work done is zero when the displacement is perpendicular to the force.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.
20. Question 201 mark

    Assertion (A): Sound travels faster in air than in steel.

    Reason (R): Sound needs a material medium to travel.

    1. A.Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
    2. B.Both Assertion (A) and Reason (R) are true, but R is not the correct explanation of A.
    3. C.Assertion (A) is true, but Reason (R) is false.
    4. D.Assertion (A) is false, but Reason (R) is true.

Section B · Very short answer

1. Question 212 marks

   Give two reasons why a wet cloth dries faster on a windy day.

2. Question 222 marks

   Write the chemical formulae of (a) calcium oxide (b) sodium carbonate.

3. OR

   Question 222 marks

   Calculate the formula unit mass of CaCl₂. (Ca = 40 u, Cl = 35.5 u)

4. Question 232 marks

   State two limitations of Rutherford's model of the atom.

5. Question 242 marks

   Why are mitochondria and plastids called semi-autonomous organelles?

6. Question 252 marks

   An athlete completes one round of a circular track of diameter 200 m in 40 s. What is the distance covered and the displacement at the end of 40 s?

7. OR

   Question 252 marks

   Why does a fielder pull his hands back while catching a fast-moving cricket ball?

8. Question 262 marks

   What is intercropping? Give one advantage.

Section C · Short answer

1. Question 273 marks

   A solution contains 40 g of common salt in 320 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.

2. Question 283 marks

   Define valency. Find the valency of (a) nitrogen (atomic number 7) (b) argon (atomic number 18).

3. Question 293 marks

   Describe the structure and function of the three types of blood components — plasma, red blood cells and white blood cells — in one line each.

4. OR

   Question 293 marks

   Name three types of simple permanent tissue in plants and give one feature of each.

5. Question 303 marks

   A bus decreases its speed from 80 km/h to 60 km/h in 5 s. Find its acceleration.

6. Question 313 marks

   What is buoyancy? Why does an iron nail sink in water but a ship made of iron floats?

7. Question 323 marks

   An object of mass 15 kg is moving with a uniform velocity of 4 m/s. What is its kinetic energy? How much work must be done to stop it?

8. OR

   Question 323 marks

   A lamp consumes 1000 J of electrical energy in 10 s. What is its power? How much energy will it use in 5 hours, in kWh?

9. Question 333 marks

   What are macro-nutrients? Name any two. Why are they called so?

Section D · Long answer

1. Question 345 marks

   (a) What are the characteristics of the particles of matter? Describe an activity to show that particles of matter have spaces between them. (b) Why does the temperature of a substance remain constant during its change of state?

2. Question 355 marks

   (a) State Newton's third law of motion with two examples. (b) A 5 kg gun fires a 50 g bullet with a velocity of 400 m/s. Find the recoil velocity of the gun.

3. OR

   Question 355 marks

   (a) Derive the relation between g (acceleration due to gravity) and G (universal gravitational constant). (b) A stone is thrown vertically upward with a speed of 20 m/s. How high will it go and how long will it take to reach the top? (g = 10 m/s²)

4. Question 365 marks

   (a) Draw (describe) the structure of a typical animal cell and name any five parts. (b) What would happen to a cell if its nucleus were removed?

Section E · Case study

1. Question 374 marks

   Case study — Echo in a valley. A group of hikers stands in a valley facing a steep cliff. One of them claps loudly and hears the echo 2 s later. The speed of sound in air that day is 340 m/s.

   (i) What is an echo? (1 mark)

   (ii) What is the minimum distance of a reflecting surface for an echo to be heard distinctly in air at 340 m/s? (1 mark)

   (iii) How far away is the cliff? Show your working. (2 marks)

   OR

   (iii) Why do echoes help bats locate obstacles in the dark? Name the kind of sound they use. (2 marks)

2. Question 384 marks

   Case study — Making magnesium oxide. In a laboratory, a student burns 2.4 g of magnesium ribbon in air and finds that 4.0 g of white magnesium oxide (MgO) is formed. (Mg = 24 u, O = 16 u)

   (i) What mass of oxygen combined with the magnesium? (1 mark)

   (ii) Which law of chemical combination does this experiment illustrate? (1 mark)

   (iii) Find the number of moles of magnesium used and the number of magnesium atoms present. (2 marks)

   OR

   (iii) Find the ratio by mass of magnesium to oxygen in MgO, and show that it is the same as the ratio from the formula. (2 marks)

3. Question 394 marks

   Case study — Bee-keeping. A farmer in Himachal Pradesh sets up boxes of honey bees near his apple orchard. He chooses the Italian bee Apis mellifera and notices that his apple yield also increases.

   (i) Why did the farmer prefer the Italian bee? (1 mark)

   (ii) What is 'pasturage' in bee-keeping? (1 mark)

   (iii) Give two reasons why the apple yield increased and bee-keeping is profitable. (2 marks)

   OR

   (iii) Name two products obtained from bee-keeping and one use of each. (2 marks)