If you say my name, I will no longer exist. What am I?

How many sides does a circle have?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Can you spot what's wrong with the following sentence?

PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.

If six children and two dogs were under an umbrella, how come none of them got wet?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

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

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

John was going on a jungle trip. He asked his wife to pack something to eat, something to drink and something to burn if he feels cold in the jungle. When John opens the backpack he found just one thing in the bag. What was it?

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.