What can you see in the middle of March and April that you can never see in any other month?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

What is the centre of gravity?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

Name a key which is hardest to turn.

What country can make you shiver?

When does a USA Potato change its nationality?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

I can turn polar bears white.
I can make anyone dance.
I can make everyone cry
I can make your hands clap
I can make you thin.
I can make you smile.
I can make you smile

Can you guess the riddle?

I am quite hot but become too cold if you remove the first two letters. What am I?