What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

Replace the question mark with the correct number below.

What you cannot hold but it is yours?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

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?

Can you find the key in the picture below?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

The owner of a popular clothing store comes up with his own method of pricing items. A vest costs $8, socks cost $10, a tie costs $6, and a blouse costs $12. Using the owner’s method, how much would a pair of underwear cost?