121. Materials like Germanium and Silicon are called
(A) Metals
(B) Semi-conductors
(C) Insulators
(D) Conductors
Correct Answer: [B] Semi-conductors.
122. Absolute zero temperature is that temperature where
(A) All matter stays in the solid state.
(B) Kinetic and potential energies of molecules become equal to each other.
(C) Water freezes to ice.
(D) All molecules of matter come to rest
Correct Answer: [D] All molecules of matter come to rest.
123. Bats can fly in the dark without hitting objects because
(A) They are guided by ultrasonic waves which they produce.
(B) Of no scientific reason.
(C) They are flying mammals.
(D) Their night vision is good
Correct Answer: [A] They are guided by ultrasonic waves which they produce..
124. A person is moving towards a plane mirror with a speed of 1 m / sec. The image will approach the moving person will relative speed
(A) 2 m/sec.
(B) 3 m/sec.
(C) 1.5 m/sec.
(D) 1 m /sec
Correct Answer: [A] 2 m/sec..
125. The current on a 100W, 200V electric bulb is
(A) 0.5 amp
(B) 22000 amp
(C) 2.2 amp
(D) 2.3 amp
Correct Answer: [A] 0.5 amp.
126. 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
Correct Answer: [D] When they are brought in contact there will be no exchange of heat.
127. 75% of a radioactive element decays in 6 hours. It's half-life period is
(A) 1/6 hours
(B) 3 hours
(C) 2 hours
(D) 4 hours
Correct Answer: [B] 3 hours.
128. RADAR is based on the principle that
(A) Sound waves are reflected by an object
(B) Sound waves are a transverse wave
(C) Radio waves are reflected by objects
(D) Sound waves can travel in the air
Correct Answer: [C] Radio waves are reflected by objects.
129. A magnifying glass or a simple microscope produces a
(A) Magnified virtual image.
(B) Diminished virtual image.
(C) Magnified real image.
(D) Virtual image near the eye, having the same size as the object
Correct Answer: [A] Magnified virtual image..
130. 10 gm. of ice at 0°C is mixed with 10 gm. of water at 0°C. The temperature of the mixture will be
(A) 10°C
(B) 0°C
(C) 1°C
(D) 5°C
Correct Answer: [B] 0°C.
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