John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

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?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

How is a fly different from a mosquito?

What do you get if you add 2 to 100 four times?

Different lights make me strange by changing me into different sizes. What am I?

Why is the longest human nose just 11 inches?

Which letter of the alphabet has the most water?

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

How can you make a TV, a bed, a dog, and a car liquid?