When we see 2 but call 10?

The dirtier I get, the whiter I look. Who am I?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

Can you solve below mathematical equation?

2^1234 - 2^1233

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Identify the next two numbers in this series.

101, 112, 131, 415, 161, 718, ???, ???

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?