What is black when you buy it, red when you use it, and gray when you throw it away?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Why is the longest human nose just 11 inches?

This is a famous paradox which has caused a great deal of argument and disbelief from many who cannot accept the correct answer. Four balls are placed in a hat. One is white, one is blue and the other two are red. The bag is shaken and someone draws two balls from the hat. He looks at the two balls and announces that at least one of them is red. What are the chances that the other ball he has drawn out is also red?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

I have an eye but still cannot see.

Who am I?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

Why is it against the law for a man living in Delhi to be buried in Mumbai?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.