1. The ratio of the moment of inertia of a ring about an axis passing through its rim and perpendicular to its plane and that about a diameter is—
(A) 1 : 4 (B) 4 : 1 (C) 1 : 2 (D) 2 : 1

2. A bottle of sodawater is grasped by the neck and swung briskly in a circle. Near which portion of the bottle do the bubbles collect ?
(A) Near the bottom (B) Near the neck
(C) In the middle of the bottle (D) Bubbles remain distributed uniformally throughout the bottle

3. If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately—
(A) 60% (B) 65% (C) 70% (D) 75%

4. The main source of solar energy is—
(A) Nuclear fission (B) Nuclear fusion (C) Gravitational contraction (D) Combustion

5. The time period of oscillation of a freely suspended magnet is 4 sec. If it is broken in length into two equal parts and one part is suspended in the same way, its time period will be—
(A) 4 sec (B) 2 sec (C) 0·5 sec (D) 0·25 sec

6. Five identical capacitors connected in series have an equivalent capacitance of 4 μF. If all of them are connected in parallel across a 400 V source, the total energy stored in them is—
(A) 2J (B) 4J (C) 8J (D) 16J

7. The absorptive power of a perfectly black body is—
(A) 1 (B) 0 (C) ∞ (D) None of these

8. A 100 g bullet, moving with a speed of 500 m/s, enters a block of ice. The mass of ice that melts is—
(A) 111·6 g (B) 74·4 g (C) 37·2 g (D) 18·6 g

9. A hollow metal sphere of radius 5 cm is charged so that the potential on its surface is 10V. The potential at the centre of the sphere is—
(A) Zero (B) 10V (C) Same as at a point 5 cm away from the surface (D) Same as at a point 25 cm away from the surface

10. If one mole of a monoatomic gas (γ = 5/3) is mixed with one mole of a diatomic gas (γ = 7/5), the value of γ for the mixture is—
(A) 1·40 (B) 1·50 (C) 1·53 (D) 3·07

11. Water rises to height of 2 cm in a capillary tube. The angle of contact is zero. The tube is now depressed further so that its length above the surface of water is only 1 cm. The apparent angle of contact now is—
(A) 0° (B) 30° (C) 60° (D) 90°

12. A body cools from 85°C to 80°C in 5 minute. The time taken to cool from 80°C to 75°C is—
(A) Less than 5 minute (B) 5 minute (C) More than 5 minute
(D) Less or more than 5 minute depending on the nature of the body

13. An electric bulb which is running at 80V d.c. mains consuming 10A current is connected across a 100V, 50 Hz a.c . supply. The inductance of the choke required is (take π = 3)—
(A) 0·01 H (B) 0·02 H (C) 0·04 H (D) 0·08 H

14. The ratio of the binding energies of the hydrogen atom in the first and the second excited states is—
(A) 1/4 (B) 4/9 (C) 4 (D) 9/4

15. The radius of a hollow metallic sphere is R. If the potential difference between its surface and a point at a distance of 3R from its centre is V, then the electric field intensity at a distance of 3R from its centre is—
(A) V/2R (B) V/4R (C) V/3R (D) V/6R

16. A ball of mass m is thrown vertically up. Another ball of mass 2m is thrown at an angle θ. If their times of ascent are equal, then the heights attained by them are in the ratio—
(A) 1 : 1 (B) 1 : cos θ (C) 2 : 1 (D) 1 : sec θ

17. If the work done in stretching a wire by 1 mm is 2J, the work necessary for stretching another wire of the same material but double the radius and half the length by 1 mm is—
(A) 16 J (B) 4 J (C) 8 J (D) (1/4) J