SECTION A: MULTIPLE CHOICE QUESTIONS [10 MARKS]
Q1. Which of the following observations confirms that a chemical reaction has taken place when quicklime is added to water?
[1]
(A) Change in color only
(B) Vigorous evolution of heat
(C) Formation of a blue precipitate
(D) Evolution of oxygen gas
Q2. What happens when dilute hydrochloric acid is added to sodium hydrogen carbonate solution?
[1]
(A) Hydrogen gas is evolved with pop sound
(B) Brisk effervescence of carbon dioxide occurs
(C) Chlorine gas is evolved with pungent smell
(D) No reaction takes place
Q3. Which metal is stored under kerosene oil to prevent it from reacting violently with atmospheric moisture and oxygen?
[1]
Q4. Which enzyme present in pancreatic juice is responsible for digesting proteins into peptones?
[1]
(A) Salivary Amylase
(B) Trypsin
(C) Lipase
(D) Pepsinogen
Q5. The gap between two adjoining neurons across which nerve impulses pass chemically is called a:
[1]
(C) Dendrite
(D) Myelin sheath
Q6. An object is placed at 2F in front of a convex lens. The nature and size of the image formed will be:
[1]
(A) Virtual, erect, magnified
(B) Real, inverted, same size
(C) Real, inverted, diminished
(D) Virtual, erect, diminished
Q7. The splitting of white light into its component colors when passed through a glass prism is known as:
[1]
(A) Reflection
(B) Dispersion
(C) Atmospheric Refraction
(D) Total Internal Reflection
Q8. Which defect of vision occurs when the eye lens loses its power of accommodation due to aging?
[1]
(A) Myopia
(B) Presbyopia
(C) Hypermetropia
(D) Astigmatism
Q9. What is the focal length of a spherical mirror whose radius of curvature is 30 cm?
[1]
Q10. Which plant hormone promotes cell division and is present in high concentration in fruits and seeds?
[1]
(C) Abscisic Acid
(D) Gibberellin
SECTION B: FILL IN THE BLANKS [10 MARKS]
Q11. The process of coating iron articles with a thin layer of zinc to prevent rusting is called ____________________. [1]
Q12. The pH range of fresh milk changes from 6 to ____________________ when it turns into curd. [1]
Q13. Non-metals generally do not react with dilute acids to evolve ____________________ gas. [1]
Q14. The functional filtering units present in human kidneys are called ____________________. [1]
Q15. Involuntary actions like blood pressure, salivation, and vomiting are controlled by the ____________________ in the hindbrain. [1]
Q16. The SI unit of power of a lens is ____________________. [1]
Q17. A concave mirror forms a virtual, erect, and enlarged image when the object is placed between the Pole and the ____________________. [1]
Q18. The phenomenon responsible for the twinkling of stars at night is atmospheric ____________________. [1]
Q19. The blue color of a clear sky is due to the ____________________ of light by atmosphere particles. [1]
Q20. The endocrine gland attached to the base of the brain that secretes Growth Hormone is the ____________________ gland. [1]
SECTION C: SHORT ANSWER QUESTIONS [10 MARKS]
Q21. Write a balanced chemical equation for the reaction that takes place when lead nitrate powder is heated in a dry boiling tube. State one observation. [2]
Q22. Why do ionic compounds have high melting and boiling points? Give two reasons. [2]
Q23. Differentiate between xylem and phloem transport in plants based on directional flow and substances transported. [2]
Q24. Define refractive index. Absolute refractive index of glass is 1.5; calculate the speed of light in glass (speed of light in vacuum = 3 × 108 m/s). [2]
Q25. Explain why the sun appears reddish during sunrise and sunset. [2]
SECTION D: LONG ANSWER & CASE STUDY QUESTIONS [10 MARKS]
Q26. [5]
(a) What is presbyopia? Mention two causes of this defect of vision.
(b) How is this vision defect corrected?
(c) A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What type and power of lens should be used to restore proper vision?
Q27. CASE STUDY BASED QUESTION: [5]
Read the passage given below and answer the questions that follow:
When an acid reacts with a base, salt and water are produced in a reaction known as neutralization. However, salts themselves are not always neutral; they can be acidic, basic, or neutral depending on the strength of the reacting acid and base. During the chlor-alkali process, electricity is passed through an aqueous solution of sodium chloride (brine), resulting in the decomposition into three important chemical industrial products used widely in manufacturing processes.
Sub-questions:
(a) Name the gas liberated at the anode during the electrolysis of brine solution.
[1]
(b) Predict the nature (acidic/basic/neutral) of an aqueous solution of ammonium chloride (NH
4Cl).
[1]
(c) Write the chemical equation for the chlor-alkali process and list one major commercial use for each of its three products.
[3]
ANSWER KEY & MARKING SCHEME
SECTION A: MCQs
| Q. No. | Correct Answer | Q. No. | Correct Answer |
|---|
| Q1 | (B) Vigorous evolution of heat | Q6 | (B) Real, inverted, same size |
| Q2 | (B) Brisk effervescence of CO2 | Q7 | (B) Dispersion |
| Q3 | (B) Sodium | Q8 | (B) Presbyopia |
| Q4 | (B) Trypsin | Q9 | (B) 15 cm |
| Q5 | (B) Synapse | Q10 | (B) Cytokinin |
SECTION B: Fill in the Blanks
| Q. No. | Answer | Q. No. | Answer |
|---|
| Q11 | Galvanization | Q16 | Dioptre (D) |
| Q12 | Less than 6 (Lower) | Q17 | Principal Focus (F) |
| Q13 | Hydrogen | Q18 | Refraction |
| Q14 | Nephrons | Q19 | Scattering |
| Q15 | Medulla (Medulla Oblongata) | Q20 | Pituitary |
SECTION C: Short Answers (2 Marks Each)
Q21: 2Pb(NO3)2 (s) → 2PbO (s) + 4NO2 (g) + O2 (g). Observation: Brown fumes of Nitrogen Dioxide gas are evolved. (1 mark for equation, 1 mark for observation)
Q22: Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions, requiring a large amount of energy to break the ionic bonds. (2 marks)
Q23: Xylem transports water and minerals unidirectionally (upward). Phloem transports photosynthesized food (sucrose) bidirectionally (upward and downward). (1 mark each)
Q24: Refractive Index is the ratio of speed of light in vacuum to speed of light in medium (n = c / v). Speed in glass v = (3 × 108) / 1.5 = 2 × 108 m/s. (1 mark definition, 1 mark calculation)
Q25: At sunrise/sunset, light travels longer distance through atmosphere. Shorter wavelengths (blue) get scattered away, leaving longer wavelength (red) to reach our eyes. (2 marks)
SECTION D: Long Answer & Case Study (5 Marks Each)
Q26: (a) Presbyopia is the decrease in eye's power of accommodation with age. Causes: weakening of ciliary muscles and diminishing flexibility of eye lens. (2 marks)
(b) Corrected using bifocal lenses (upper concave, lower convex). (1 mark)
(c) Concave lens required. f = −1.2 m; Power P = 1 / f = 1 / (−1.2) = −0.83 D. (2 marks)
Q27: (a) Chlorine gas (Cl2). (1 mark)
(b) Acidic nature (pH < 7). (1 mark)
(c) Equation: 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g). Uses: NaOH (soaps/detergents), Cl2 (water treatment/PVC), H2 (fuel/margarine). (3 marks)
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