What does below science rebus mean?

Ag Ag Ag
Ag SPOON Ag
Ag Ag Ag

Solve the puzzle by telling what does below picture means.

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

This is a most unusual paragraph. How quickly can you find out what is so unusual about it? It looks so ordinary, you'd think nothing was wrong with it. Actually, nothing IS wrong with it. But it is not as ordinary as you might think. If you think about it for a bit, you will find out why it is truly so unusual. So what is it? What is so unordinary about this paragraph?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

What Time Should the last watch show in the below figure?