What does it mean?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

John has eleven friends. He has a bowl containing eleven apples. Now He wants to divide the eleven apples among his friends, in such a way that an apple should remain in his bowl.
How can He do it?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

What always comes into a house through the keyhole?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

Can you count the number of triangles in the picture below?

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

Solve The below Equation:

ALFA + BETA + GAMA = DELTA

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?