Science · Sample Paper 1

General instructions

Section A · Objective

1. Question 11 mark

   The reaction 2Mg + O₂ → 2MgO is an example of a

   1. A.combination reaction
   2. B.decomposition reaction
   3. C.displacement reaction
   4. D.double displacement reaction
2. Question 21 mark

   The reaction Fe + CuSO₄ → FeSO₄ + Cu is an example of a

   1. A.combination reaction
   2. B.decomposition reaction
   3. C.displacement reaction
   4. D.double displacement reaction
3. Question 31 mark

   The pH of a neutral solution at 25 °C is

   1. A.0
   2. B.1
   3. C.7
   4. D.14
4. Question 41 mark

   The chemical formula of baking soda is

   1. A.Na₂CO₃
   2. B.NaHCO₃
   3. C.NaOH
   4. D.CaOCl₂
5. Question 51 mark

   Which metal is stored under kerosene to prevent accidental fires?

   1. A.Sodium
   2. B.Magnesium
   3. C.Aluminium
   4. D.Copper
6. Question 61 mark

   Which of the following non-metals is a good conductor of electricity?

   1. A.Sulphur
   2. B.Iodine
   3. C.Graphite
   4. D.Phosphorus
7. Question 71 mark

   The general formula of alkynes is

   1. A.CₙH₂ₙ₊₂
   2. B.CₙH₂ₙ
   3. C.CₙH₂ₙ₋₂
   4. D.CₙHₙ
8. Question 81 mark

   The functional group present in ethanoic acid is

   1. A.–OH (alcohol)
   2. B.–COOH (carboxylic acid)
   3. C.–CHO (aldehyde)
   4. D.–CO– (ketone)
9. Question 91 mark

   Photosynthesis takes place in the

   1. A.mitochondria
   2. B.chloroplasts
   3. C.ribosomes
   4. D.nucleus
10. Question 101 mark

    Which blood vessel carries oxygenated blood from the lungs to the heart?

    1. A.Pulmonary artery
    2. B.Pulmonary vein
    3. C.Aorta
    4. D.Vena cava
11. Question 111 mark

    Which plant hormone promotes cell division?

    1. A.Auxin
    2. B.Gibberellin
    3. C.Cytokinin
    4. D.Abscisic acid
12. Question 121 mark

    Binary fission is seen in

    1. A.Amoeba
    2. B.Hydra
    3. C.Rhizopus
    4. D.Planaria
13. Question 131 mark

    In Mendel's monohybrid cross, the phenotypic ratio in the F₂ generation is

    1. A.1 : 2 : 1
    2. B.3 : 1
    3. C.9 : 3 : 3 : 1
    4. D.1 : 1
14. Question 141 mark

    The focal length of a concave mirror whose radius of curvature is 20 cm is

    1. A.5 cm
    2. B.10 cm
    3. C.20 cm
    4. D.40 cm
15. Question 151 mark

    The SI unit of electrical resistance is

    1. A.volt
    2. B.ampere
    3. C.ohm
    4. D.watt
16. Question 161 mark

    Which of the following is biodegradable?

    1. A.Vegetable peels
    2. B.Plastic bags
    3. C.Glass bottles
    4. D.Aluminium foil
17. Question 171 mark

    Assertion (A): The blue colour of copper sulphate solution fades when an iron nail is dipped in it.

    Reason (R): Iron is more reactive than copper and displaces it from copper sulphate solution.

    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): The clear sky appears blue.

    Reason (R): Very fine particles in the atmosphere scatter blue light (shorter wavelength) more strongly than red light.

    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): A compass needle placed near a current-carrying wire gets deflected.

    Reason (R): A current-carrying conductor produces a magnetic field around it.

    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): Depletion of the ozone layer is a cause for concern.

    Reason (R): At ground level, ozone is a deadly poison.

    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

   Why should a magnesium ribbon be cleaned before burning it in air? Write the balanced equation for the reaction.

2. OR

   Question 212 marks

   Write balanced chemical equations for: (a) hydrogen + chlorine → hydrogen chloride (b) barium chloride + aluminium sulphate → barium sulphate + aluminium chloride

3. Question 222 marks

   Why does dry HCl gas not change the colour of dry blue litmus paper?

4. Question 232 marks

   Why is diffusion insufficient to meet the oxygen requirement of multicellular organisms like humans?

5. OR

   Question 232 marks

   State two functions of the hydrochloric acid secreted in the stomach.

6. Question 242 marks

   A concave mirror produces a real image three times the size of an object placed 10 cm in front of it. Where is the image located?

7. Question 252 marks

   Resistors of 4 Ω and 12 Ω are connected in parallel across a 6 V battery. Find (a) the equivalent resistance (b) the total current.

8. Question 262 marks

   Why are decomposers important in an ecosystem?

Section C · Short answer

1. Question 273 marks

   Identify the type of each reaction: (a) CaCO₃ → CaO + CO₂ (on heating) (b) NaOH + HCl → NaCl + H₂O (c) Zn + 2HCl → ZnCl₂ + H₂

2. Question 283 marks

   Show the formation of sodium chloride by the transfer of electrons. State two properties of ionic compounds.

3. OR

   Question 283 marks

   What are roasting and calcination? Write one chemical equation for each, and one for the reduction of zinc oxide with carbon.

4. Question 293 marks

   What is a homologous series? State two of its characteristics and write the formula of the next homologue of C₂H₆.

5. Question 303 marks

   What is a reflex action? Describe the path of a reflex arc.

6. OR

   Question 303 marks

   Name the hormone and the gland involved in each case: (a) regulating blood sugar level (b) whose deficiency causes goitre (c) regulating growth of the body

7. Question 313 marks

   In pea plants, tallness (T) is dominant over shortness (t). A pure tall plant is crossed with a pure short plant. Show the F₁ and F₂ generations and give the phenotypic and genotypic ratios in F₂.

8. Question 323 marks

   What is myopia? State two causes and how it is corrected.

9. Question 333 marks

   State Fleming's left-hand rule. Name one device that works on this principle.

Section D · Long answer

1. Question 345 marks

   (a) What is a neutralisation reaction? Give one example.

   (b) Write the chemical name, formula and one use of: (i) bleaching powder (ii) washing soda (iii) plaster of Paris

2. OR

   Question 345 marks

   (a) How is sodium hydroxide produced in the chlor-alkali process? Write the equation.

   (b) Why is it called the chlor-alkali process?

   (c) State one use each of the three products.

3. Question 355 marks

   (a) Describe the process of fertilisation in flowering plants and the changes that follow it.

   (b) Name any two methods of contraception.

4. OR

   Question 355 marks

   Describe double circulation of blood in human beings. Why is it necessary?

5. Question 365 marks

   (a) An object 5 cm tall is placed 25 cm in front of a convex lens of focal length 10 cm. Find the position, nature and size of the image.

   (b) Define the power of a lens and find the power of this lens.

6. OR

   Question 365 marks

   (a) State Ohm's law.

   (b) Three resistors of 2 Ω, 3 Ω and 6 Ω are available. Find the equivalent resistance when they are connected (i) in series (ii) in parallel.

   (c) A current of 2 A flows through a 5 Ω resistor for 10 s. Calculate the heat produced.

Section E · Case study

1. Question 374 marks

   Case study — Electricity at home. In our homes, electricity is supplied at 220 V. Appliances such as bulbs, fans and heaters are connected in parallel, and the circuit is protected by a fuse or MCB. An electric room heater is rated 1000 W, 220 V.

   (i) Find the current drawn by the heater. (1 mark)

   (ii) Why are household appliances connected in parallel? (1 mark)

   (iii) The heater is used for 2 hours every day for 30 days. Find the energy consumed in kWh and its cost at ₹6 per unit. (2 marks)

   OR

   (iii) What is the function of a fuse? Why is it made of a material with a low melting point? (2 marks)

2. Question 384 marks

   Case study — A food chain. In a grassland, the following food chain is observed: grass → grasshopper → frog → snake → eagle. The grass traps 10,000 J of energy from sunlight.

   (i) At which trophic level is the frog? (1 mark)

   (ii) Using the 10% law, how much energy is available to the frog? (1 mark)

   (iii) Why do food chains generally have only three or four trophic levels? (2 marks)

   OR

   (iii) If a pesticide enters this food chain, which organism will have its highest concentration, and why? (2 marks)

3. Question 394 marks

   Case study — Soaps and detergents. Riya noticed that soap formed very little lather when she washed clothes with water from the well, but a detergent worked well. She learnt that the well water was 'hard'.

   (i) Why does soap form little lather in hard water? (1 mark)

   (ii) Give one advantage of detergents over soaps. (1 mark)

   (iii) Explain how soap removes oily dirt, with reference to micelles. (2 marks)

   OR

   (iii) What is esterification? Write the equation for the reaction between ethanol and ethanoic acid and give one use of esters. (2 marks)