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

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

I cannot talk, but I always reply when spoken to. What am I?

The captain of a ship was telling this interesting story: "We travelled the sea far and wide. At one time, two of my sailors were standing on opposite sides of the ship. One was looking west and the other one east. And at the same time, they could see each other clearly." How can that be possible?

Replace the question mark with the correct number.

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

Find the value of "?" in the ball picture Riddle below: