How many times can you subtract the number two from the number fifty?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

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

Before Mount Everest was discovered, what was the highest mountain in the world?

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

What you cannot hold but it is yours?

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?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?