What does below chemistry rebus means?

What kind of tree can you carry in your hand?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Rebus Puzzle Definition: A rebus is an illusion device that uses pictures to represent words or parts of words.
What does This Rebus Puzzle Identify?

John and Jill are madly in love with each other. To remind Jill of his pure love, John wants to send her a ring by post but in their country where burglary is quite prominent, any package that is not locked comes under the risk of being stolen for the contents.

John and Jill possess many padlocks but neither one of them has the other key.

Can you find a way John can send the ring to Jill safely?

A cat had three kittens: Snophy, Topsy and Jorden. What was the mother's name?

There is something which you can be arrested for attempting but not for successfully completing.

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

There is a number which when you multiply by 3 and subtract 2 from the result, then the resulting number is the reverse of the actual number.

What is the smallest number that stands true on the statement?