2531: Why are dewdrops not formed on a cloudy night?
(a) Clouds absorb the radiation released from the Earths surface.
(b) Clouds reflect back the Earths radiation.
(c) The Earths surface would have low temperature on cloudy nights.
(d) Clouds deflect the blowing wind to ground level.
2532: Which of the following can be threats to the biodiversity of a geographical area?
1. Global warming
2. Fragmentation of habitat
3. Invasion of alien species
4. Promotion of vegetarianism
Select the correct answer using the codes given below :
(a) 1, 2 and 3 only
(b) 2 and 3 only
(c) 1 and 4 only
(d) 1, 2, 3 and 4
2533: How many minimum number of colours will be required to paint all the sides of a cube without the adjacent sides having the same colours?
(a) 3
(b) 4
(c) 5
(d) 6
2534: A walks around a circular field at the rate of one round per hour while B runs around it at the rate of six rounds per hour. They start in the same direction from the same point at 7.30 a.m. They shall first cross each other at
(a) 8.30 a.m.
(b) 8.10 a.m.
(c) 7.48 a.m.
(d) 7.42 a.m.
2535: Diffusion of light in the atmosphere takes place due to
(a) Carbon dioxide
(b) Dust particles
(c) Helium
(d) Water vapours