I am white when I am dirty, and black when I am clean. What am I?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

What does the below image rebus riddle means ?

Can it be possible to build a house that has all its four walls facing towards the South?

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

There is so small cabin inside a deep forest.
All the forest burned out to worst possible but the inside of the cabin is still the same.
However all the person inside the cabin die.

How come ?

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

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Which alphabet letter is a question?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13