What does below chemistry rebus means?

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?

How is a fly different from a mosquito?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

As we know that white starts the game of chess. Can you find the scenario shown in the picture below is possible when all the white pieces are at the original place while the black pawn is not as in the below picture?

Spot the cat in the picture below

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?