If a wheel has 54 spokes, how many spaces are there between the spokes?

An inspection by the superintendent of St. Joseph School was scheduled on the next day. The class teacher Jenifer knew that he would be asking questions from her class and she would have to choose a pupil to answer. To offer a perfect impression over him, the teacher explained certain instructions to the students to maximise the chances of getting correct answer every time.

What did she say to the students?

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?

You can hear me, but you can't touch or see me.

What am I?

What does it mean?

It belongs to you, but other people use it more than you do. What is it?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

I don't get anymore wetter, no matter how much rain falls on me.

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