The more of this there is, the less you see. What is it?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

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

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?