What is the word or phrase?

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

Which of the below owl is odd one out?

One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

A red house is made out of red bricks. A yellow house is made out of yellow bricks. And, a blue house is made out of blue bricks. So, what is a greenhouse made of?

You have two rectangular wires.

Both of them have property that when you light the fire from one end , it will take 60 minutes to get completely burn.

However, they do not burn at consistent speed (i.e it might be possible 1st 20% burn in 50 minutes and 80% can burn in 10 minutes).

So how could you measure 45 minutes ?

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

You board a train. The train will have to enter a tunnel soon. You are claustrophobic. Which place is the best for you to sit?