# WBCS Prelims and Mains MCQs on General Science (Physics) P12

Page 12

1532111. When the water cools from 7°C to 0°C
A
It first contracts and then expands
B
It first expands and then contracts
C
It contracts only
D
It expands only
A
Correct Answer: A. It first contracts and then expands
1574112. X-rays are
A
Electromagnetic wave of long wavelength
B
Electromagnetic wave of short wavelength
C
Electromagnetic wave
D
None of the above
B
Correct Answer: B. Electromagnetic wave of short wavelength
1591113. Solar energy is produced by the process of
A
Explosion
B
Contraction
C
Fusion
D
Fission
C
1585114. In a p-type semiconductor, which is the main carrier of electricity?
A
Electrons
B
Negative Ions
C
Positive holes
D
Positive Ions
C
1549115. The surface of the water in a lake is going to freeze. The temperature of water at the bottom is
A
4°C
B
0°C
C
More than 4°C
D
Less than 4°C
A
1580116. The temperature of two bodies being equal means
A
Their heat capacities are the same
B
Their specific heats are the same
C
Their heat contents are the same
D
When they are brought in contact there will be no exchange of heat
D
Correct Answer: D. When they are brought in contact there will be no exchange of heat
1515117. An iron ball and a wooden ball of the same mass are released from a height h in air. Neglecting viscous drag of air
A
There is an equal probability for the wooden and iron ball to hit the ground earlier.
B
Both will reach the ground at the same time.
C
The iron ball will hit the ground earlier.
D
The wooden ball will hit the ground earlier
B
Correct Answer: B. Both will reach the ground at the same time.
1465118. Both ends of the tube of a Telescope have
A
Plano-convex lens
B
Piano concave lens
C
Convex lens
D
Concave lens.
C
1496119. A shaving brush is dipped in water. When taken out the hairs of the brush are seen to be drawn together due to
A
the elasticity of the hairs of the brush.
B
the temperature difference between air and water.
C
the surface tension of water.
D
the viscosity of water
C
Correct Answer: C. the surface tension of water.
1611120. The reverberation of sound in a half is due to continued
A
diffraction
B
absorption
C
reflection
D
interference
D