I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

What am I?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?

Count the number of squares in the picture below.

Give it food and it will live; give it water and it will die.

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

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

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

What is full of holes but still holds water?

There is a place where if I stand up straight, I will still be considered sideways.