What is the centre of gravity?

Can you decipher the below rebus?

PBLUESAISNUERSES

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

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

No matter how little or how much you use me, you change me every month. What am I?

Replace the question mark in the picture below.

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

With the help clues provided in the image, can you find the 5 digit key?

Can you make a six-letter word using the letters N, A and B ?