Watching the sunset on a beach, one can see for several minutes after it has 'actually set'. Explain.

The sun is seen a little before it rises and for a short while after it sets. Explain, why ?

Can any one see in the dark?

Ornithologists observed decline in the bird population in an area near a lake after the setting of an industrial unit in the same area. Explain the cause responsible for the decline observed.

The sun appears before the sun rise and after sun set for few minutes, why?

Prove that if a set has only one clement then it has 2 subsets.

What is the minimum size of the plane mirror , in which a man can see his full height?Explain.

On a hot summer day in desert ,one sees the relected image of the distant objects.Explain,why.

Find the horse power of child if he can chew 10 grams ice in one minute.

There is a myth that immediately after heavy rains in forests, mushrooms appear in large number and make a very large ring or cirle, which may be several metres in diameter. These are called as 'Fairy rings'. Can you explain this myth of fairy rings in biological terms?