What always comes into a house through the keyhole?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

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?

I look at you, you look at me I raise my right, you raise your left. What am I?

An artist while painting a scenic beauty, decides to paint three layers of blue colour on the sky.

Which layer will go on the first?

When it is alive we sing, when it is dead we clap our hands. What is it?

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

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

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