7 Common Causes of Joint Pain in Seniors

 

10th Class Board Examination - Physical Science Mock Test

Section A: Multiple Choice Questions (1 Mark Each)

1. The focal length of a plane mirror is: A) 0 B) Infinite C) 25 cm D) -25 cm

2. Which of the following is an endothermic process? A) Dilution of sulphuric acid B) Sublimation of dry ice C) Condensation of water vapours D) Respiration in human beings

3. The SI unit of electrical resistivity is: A) Ω (Ohm) B) Ω·m (Ohm-meter) C) Ω/m (Ohm per meter) D) A/m (Ampere per meter)

4. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solutions would reverse the change? A) Baking powder B) Lime C) Ammonium hydroxide solution D) Hydrochloric acid

5. The defect of vision in which a person cannot see distant objects clearly is called: A) Hypermetropia B) Presbyopia C) Myopia D) Cataract

6. Which of the following metals is a liquid at ordinary room temperature? A) Sodium B) Barium C) Mercury D) Lead

7. The magnetic field inside a long straight solenoid-carrying current: A) is zero B) decreases as we move towards its ends C) increases as we move towards its ends D) is the same at all points

8. The functional group present in Propanal is: A) -OH (Alcohol) B) -COOH (Carboxylic acid) C) -CHO (Aldehyde) D) >C=O (Ketone)

9. The power of a convex lens of focal length 50 cm is: A) +2 D B) -2 D C) +0.5 D D) -0.5 D

10. Plaster of Paris is obtained by heating which of the following substances? A) Bleaching powder B) Gypsum C) Limestone D) Baking soda

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Section B: Short Answer Questions (2 Marks Each)

11. State the two laws of reflection of light.

12. What is a neutralization reaction? Give one clear chemical equation as an example.

13. Why do stars twinkle while planets do not?

14. Why do we apply paint on iron articles? Explain briefly.

15. An electric heater of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 seconds.

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Answer Key & Solutions

Section A: MCQs

1. B (Infinite)

2. B (Sublimation of dry ice)

3. B (Ω·m)

4. D (Hydrochloric acid)

5. C (Myopia)

6. C (Mercury)

7. D (is the same at all points)

8. C (-CHO)

9. A (+2 D) Calculation: Power = 100/f(in cm) = 100/50 = +2 Diopters.

10. B (Gypsum)

Section B: Short Answers Answer 11: The two laws of reflection of light are: (i) The angle of incidence is always equal to the angle of reflection (∠i = ∠r). (ii) The incident ray, the reflected ray, and the normal to the mirror at the point of incidence all lie in the same plane.

Answer 12: A reaction in which an acid and a base react with each other to form salt and water is called a neutralization reaction. Example: NaOH (Base) + HCl (Acid) → NaCl (Salt) + H₂O (Water).

Answer 13: The twinkling of stars is due to the atmospheric refraction of starlight. As star light enters the earth's atmosphere, it undergoes continuous refraction due to changing air densities, causing the apparent position of the star to fluctuate and the light to waver. Planets are much closer to the earth and act as extended sources of light, so the variations in light coming from them average out to zero, effectively canceling the twinkling effect.

Answer 14: Paint is applied on iron articles to prevent them from rusting. Rusting occurs when iron reacts with oxygen and moisture present in the air. The coat of paint cuts off the direct contact of the iron surface with the atmosphere, thereby preventing corrosion.

Answer 15: Given: Resistance (R) = 20 Ω, Current (I) = 5 A, Time (t) = 30 s. Using Joule's Law of Heating, Heat (H) = I²Rt H = (5)² × 20 × 30 H = 25 × 20 × 30 H = 15,000 Joules (or 15 kJ).