Can you find a number that lies one third of the distance between 1/3 and 2/3?

Can you place six X (crosses) in below board without making three in a row in any way ?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

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?

What's the only room from which no one can enter or leave

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

What is more useful when it is broken?

If your uncle’s sister is not your aunt, what relation is she to you?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?