How many sides does a circle have?

I am white when I am dirty, and black when I am clean. What am I?

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

Which point will the car reach to go out?

What jumps when it walks and sits when it stands?

Fate has decided that you will only be pleased to meet me when you need me

Maybe that is why, when I am working, I start working

However annoying I may be to the regulars, the little ones are always inspired

I will always be waiting if you try to reach me

How many of you can guess my name, let me see

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

What breaks yet never falls, and what falls yet never breaks?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

The more of this there is, the less you see. What is it?