Can you replace the question mark with the correct number?

You see me once in June, twice in November, and not at all in May. What am I?

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

What does below rebus means ?

Replace the question mark in the picture below.

Forwards I am heavy, backward I am not. What am I?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A Shopkeeper sold a few chickens to four different customers on a particular day. It was such that each customer purchased half of the remaining chickens and half the chicken more.

Can you find out how many chicken were sold by the shopkeeper on that day if we tell you that the fourth customer bought a single chicken ?

Can you find a rabbit in the given picture?

Take away the whole and some still remain. What is it?