What does below chemistry rebus means?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Identify the hidden meaning behind this picture?

In the picture that is attached with this question, you can find a square which comprises of four little squares inside it. Consider this square to be made with matchsticks. You have to remove two matchsticks such that only two squares remain instead of five.How will you do it ?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

What has a bottom at the top?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?