What is both possible and impossible at the same time?

Solve the following series:
AZ, GT, MN, __, YB

What does this below rebus puzzle mean?

A Shopkeeper collects 71 rupees in the form of 20 paisa and 25 paisa.
He collects a total of 324 coins.

Can you tell me how many number of 20-paisa and 25-paisa he got?

They are the five precious gems of an everyday sort and all can be found on a Tennis Court. Who are they?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

A bomb goes off.
Carnage.
One person, only a few feet away, survives! How can this be?

Why do you find that most of the buildings are deprived of the 13th floor?

A pet show was happening in my locality. I went down along with my kids. In that show, I noticed that all except two of the entries were cats. All except two were dogs and all except two were Monkeys.

Can you find out how many of each animals were present in that pet show?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?