611. The sun appears red at sunrise and sunset while it appears white at noon, because
A. Of refraction
B. It is cooler at sunrise and at sunset
C. Of scattering of light due to dust particles and air molecules
D. None of these

612. An astronaut inside a spacecraft is in a state of weightlessness. This implies that
A. The mass of the astronaut is reduced to zero
B. Gravity inside the space craft ceases to act
C. the astronaut and the space craft are both in a free-falling state
D. None of these

613. An iceberg is floating in sea. How much of its mass will remain above the surface of water?
A. One tenth
B. One fifth
C. One Fourth
D. None of these

614. Most of the ozone in the atmosphere is concentrated in the
A. Mesosphere
B. Troposphere
C. Stratosphere
D. None of these

615. The cow’s milk contains how much amount of water in terms of percentage?
A. 60%
B. 65%
C. 80%
D. None of these

616. T.V. transmission cannot cover a very large area because
A. The strength of T.V waves is very limited
B. The shape of the earth is spherical
C. the air is not good conductor of light and sound/waves
D. None of these

617. The Green House Effect is caused by an excess of
A. Carbon dioxide
B. Carbon monoxide
C. Carbon tetra oxide
D. None of these

618. Bats can also fly in dark because they are capable of taking the help of
A. Ultraviolet Waves
B. Ultrasonic Waves
C. Electromagnetic Waves
D. None of these

619. What is ‘Stealth Technology’?
A. A device which when attached to an aircraft makes it invisible on the radar
B. A coating which reduces the visibility of an aircraft on a radar
C. A technology by which it is possible for the aircraft to spy in the enemy air space
D. None of these

620. The primary function of the feathers in birds is to
A. Provide insulation for preserving body heat
B. Provide striking surface to the wings for flying
C. Make the surface body waterproof
D. None of these