How can you take 2 from 5 and leave 4?

Which number should replace the question mark?

Can you count the number of triangles in the given figure?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

A prisoner is told: "If you tell a lie, we will hang you and if you tell the truth, we will shoot you." What did the prisoner say to save himself?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?