What is black when you buy it, red when you use it, and gray when you throw it away?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

What do you answer even though it never asks you questions?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

There was a kingdom in which the king had no heir to take over his thrown. Even the queen was dead and he himself was on the verge of dying. He thought about it and then summoned all of the teenagers. He gave one seed each to all of them and asked them to grow the plant. He announced that the one with the most beautiful plant will become the king/queen of the empire after the death of the king.

After a month, all of them were called. The king looked at all of the plants but announced the girl with an empty pot as the queen of the empire. Why?

What word is identified by the below rebus?

Your Your Your Your Your
Your Your Your Your Your

An ape is trying to climb on a pole that is 60 feet high. Due to the slippery surface, the ape climbs 3 feet in a minute only to slip back 2 feet.

How much time do you think the monkey will take to reach the top of the pole?

Which letter of the alphabet has the most water?

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?