Model Paper 3 — Physics STD 12 Science — Question

An example of a diamagnetic substance is

(a) Aluminium

(b) Copper

(c) Iron

(d) Nickel

A source of electromotive force (emf) is a:

If the current in the circuit for heating the filament is increased, the cutoff wavelength:

Diffraction effects are easier to notice in the case of sound waves than in the case of light waves because

(a) Sound waves are longitudinal	(b) Sound is perceived by the ear
(c) Sound waves are mechanical waves	(d) Sound waves are of longer wavelength

Electric potential at an equatorial point of a small dipole with dipole moment  P (r, distance from the dipole) is

(a) Zero

(b)

(c)

(d)

In one average-life:

1. Half the active nuclei decay.
2. Less than half the active nuclei decay.
3. More than half the active nuclei decay.
4. All the nuclei decay.

Consider a collision between an oxygen molecule and a hydrogen molecule in a mixture of oxygen and hydrogen kept at room temperature. Which of the following are pcssible?

1. The kinetic energies of both the molecules increase.
2. The kinetic energies of both the molecules decrease.
3. The Kinetic energy of the oxygen molecule increases and that of the hydrogen molecule decreases.
4. The kinetic energy of the hydrogen molecule increases and that of the oxygen molecule decreases.

The first law of thermodynamics is a statement of:

1. Conservation of heat.
2. Conservation of work.
3. Conservation of momentum.
4. Conservation of energy.

A body at rest breaks into two pieces of equal masses. The parts will move

1. In same direction.
2. Along different lines.
3. In opposite directions with equal speeds.
4. In opposite directions with unequal speeds.