What does below chemistry rebus means?

What can you see in the middle of March and April that you can never see in any other month?

You have two jars of chocolates labelled as P and Q. If you move one chocolate from P to Q, the number of chocolates on B will become twice the number of chocolates in A. If you move one chocolate from Q to P, the number of chocolates in both the jars will become equal.

Can you find out how many chocolates are there in P and Q respectively?

John was drowned by he was not wet. How?

Can you Find and name the hidden bird in the picture below ?

In the following series, a set of numbers is progressing with a particular pattern. Can you deduce that pattern and find the missing set?

(2 + 6), (21 + 6), (58 + 6), (119 + 6), ___

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

What do you see in the image below

Our product and our sum always give the same answer. Who are we?

Can you find out the remainder when 3^300 is divided by 5?