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

Replace the question mark with the correct number in the below-given picture?

I have branches, but no fruit, trunk or leaves. What am I?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

I make two people out of one. What am I?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

French Police inspects a room where there are no windows, no doors, no tables and is almost empty expect there is just a puddle of water. They found a dead man who obviously hung herself from the ceiling, but they are not able to figure out how this had happened.

John and Jacob entered the crime scene and easily able to solve the case.

How did the man die?

If eleven plus two equals one, what does nine plus five equal?