What's the only room from which no one can enter or leave

In the picture that is attached with this question, you can find a square which comprises of four little squares inside it. Consider this square to be made with matchsticks. You have to remove two matchsticks such that only two squares remain instead of five.How will you do it ?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

Why is a river so rich ?

Christina is practising her dance steps along with her friends. In a particular sequence, all of them form a row. At that point, Niharika is standing in the 4th position from either end of the row.
Can you find out how many girls are practising together?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

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?

Can you count the number of children in the picture below