What has many keys but can’t open a single lock?

Forwards I am heavy, backward I am not. What am I?

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?

Can you find a five letter word that is left with only two letters if one is removed?

A dead body is found outside a multi-story multinational company. The case is reported and a homicide detective is called on the crime scene.

He looks at the body and then towards the building. From the position of the body, it is evident that the victim committed suicide. He goes to the first floor of the building and then walks in the direction of the dead body, opens the window and toss a coin in the air.

He goes to second floor and again repeats the process. He keeps doing this till he is done on all the floors. Then he returns back to the floor and tells his team that it is a murder.

How in heaven did he deduce that?

Which number should replace the question mark?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

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?

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

There is a place where if I stand up straight, I will still be considered sideways.