Which of the following is not luminous object?

• A. The sun
• B. The moon
• C. light candle
• D. Star

A person can focus objects when they lie beyond 75 cm from his eyes. The focal length of the lens required to reduce his least distance of distinct vision to 25 cm is?

• A) 37.50 cm
• B) 75.00 cm
• C) 18.75
• D) 25.00 cm

Which of the following is not correct about the Rutherford’s model of an atom?

• A. The mass of an atom is concentrated around the nucleus
• B. The nucleus of an atom is positively charged
• C. The nucleus is surrounded by the electron cloud
• D. The model is applicable to atoms with only one electron in the outer shell

a. A projectile is fired at an angle, θ, to the horizontal with velocity, u. Show that at any time, t, during the motion, the: i. horizontal component of the velocity is independent of t;

ii. vertical component of the velocity depends on t.

b. State the assumption on which projectile motion is based.

Explanation

i. From v = u + gt:

\(u_x\) = ucosθ, g = 0 (horizontal component is not affected by gravity)

\(v_x\) = ucosθ + (0)t

∴ \(v_x\) = ucosθ

ii. \(v_y = u_y + gt\)

∴ \(v_y = usinθ + gt\)

b. It assumes that the only force acting on the projectile is gravity, and there are no other forces, such as air resistance or drag, affecting its motion.

List three advantages of fluorescent tubes over filament bulbs.

At what respective value of a, b, and c would the unit of work, the joule, be dimensionally similar to M^a L^b T^c?

• A. 1, – 2, 1
• B. 1, 2, – 2
• C. 1, 1, –2
• D. 2, 2, 1

Explain why water in a narrow glass tube has a concave meniscus while mercury, in the same tube, has a convex meniscus.

Refraction of lights differs from reflection in that, in refraction i. at least two media are involved ii. there is a change in the direction of the ray iii. the speed of the ray changes. Which of the statements above is/are correct?

• A. i only
• B. i ad ii only
• C. ii and iii only
• D. i and iii only

(a) State two differences between boiling and evaporation.

(b) A closed inexpansibie vessel contains air saturated with water vapour at 77°C. The total pressure in the vessel is 1007 mmHg. Calculate the new pressure in the vessel if the temperature is reduced 1.2 27°C. [ The s.v.p. of water at 77°C and 27°C respectively are 314 mmHg and 27 mmHg. Treat the air in the vessel as an ideal gas]

(c) The lengtn of a zinc rod at 23°C is 200 m. Calculate the increase in length of the rod when its temperature rises to 33°C. [ expansivity of zinc = 2.6 x 10\(^{-5}\) K\(^{-1}\)]

(d) Explain with there is no temperature change when a solid being heated changes into liquid at its melting point.

Which of the following statements give the TRUE difference between evaporation and boiling? i. Evaporation occurs at all temperatures while boiling occurs at a fixed temperature for a given pressure. ii. Evaporation is a surface phenomenon while boiling is an interior phenomenon. iii. Evaporation is affected by surface area while boiling is not.

• A. i and ii only
• B. i and iii only
• C. ii and iii only
• D. i, ii, iii.