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

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

If you say my name, I will no longer exist. What am I?

What you cannot hold but it is yours?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

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

Explain?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

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

John was going on a jungle trip. He asked his wife to pack something to eat, something to drink and something to burn if he feels cold in the jungle. When John opens the backpack he found just one thing in the bag. What was it?

What is more useful when it is broken?