Prelims

Which of the following weather conditions is indicated by a sudden fall in barometer reading ?

Consider the following statements : A simple pendulum is set into oscillation. Then I. the acceleration is zero when the bob passes through the mean position. II. in each cycle the bob attains a given velocity twice. III. both acceleration and velocity of the bob are zero when it reaches its extreme position during its oscillation. IV. the amplitude of oscillation of the simple pendulum decreases with time. Which of these statements are correct ?

Cloudy nights are warmer compared to clear cloudless nights, because clouds

The mass of a body on Earth is 100 kg (acceleration due to gravity, ge – 10 m/s2). If acceleration due to gravity on the Moon ge/6, then the mass of the body on the moon is

Who is the scientist in whose honour the “Chandra” X-ray telescope has been named ?

Consider the following statements : In a nuclear reactor, self-sustained chain reaction is possible, because I. more neutrons are released in each of the fission reactions. II. the neutrons immediately take part in the fission process. III. the fast neutrons are slowed down by Graphite. IV. every neutron realeased in the fission reaction initiates further fission. Which of these statements are correct ?

When water is heated from 0°C to 10°C, its volume

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece. Reason (R): The density of copper is more than that of glass.

Assertion (A): The boiling point of water decreases as the altitude increases. Reason (R): The atmospheric pressure increases with altitude.

When lightwaves pass from air to glass, the variables affected are