Question 4811:

How much heat is absorbed when a block of copper of mass \(0.05 \mathrm{~kg}\) and specific capacity 390\(J\mathrm{kg}-1 \mathrm{~K}-1\) is heated from \(20^{\circ} \mathrm{C}\) to \(70^{\circ} \mathrm{C}\) ?

A. \(3.98 \times 10^{-1} \mathrm{~J}\)
B. \(9.75 \times 10^{2} \mathrm{~J}\)
C. \(3.98 \times 10^{3} \mathrm{~J}\)
D. \(9.75 \times 10^{3} \mathrm{~J}\)

Question 4812:

A block of ice floats on water inside a container. If the block of ice gets a container. If the block of ice gets completely melted, the level of water in the container will ____________

A. Increase
B. Remain the same
C. Decrease
D. First decreases and then increase

Question 4813:

The space between the double glass walls of a thermos flask is evacuated and the two surfaces facing the evacuated spaces are silvered. The residual source of heat loss takes place by ____________

A. Convection
B. Radiation from the surfaces
C. Conduction through the stopper and the glass
D. Conduction across the walls

Question 4814:

Which of the following characteristics of wave is used in the measurement of the depth of the sea?

A. Diffusion
B. Interference
C. Refraction
D. Reflection

Question 4815:

What is the frequency of the sound made by a siren having a disc with 32 holes and making 25 revolution per second?

A. \(80 \mathrm{~Hz}\)
B. \(600 \mathrm{~Hz}\)
C. \(800 \mathrm{~Hz}\)
D. \(1600 \mathrm{~Hz}\)