John is the son of Jacob.
So,
Jacob is the_____of John's father?

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?

Why Wine Glass Stem is so long?

Out of three Friends John, Jacob and Jonny one of them is a king, one is a bureaucrat, and one is a Spy.

The king always tells the truth, the bureaucrat always lies, and the Spy can either lie or tell the truth.

John says: Jonny is a bureaucrat
Jacob says: John is a king
Jonny says: I am a Spy

Tell me, Who is the king, who is the bureaucrat, and who is the Spy?

What is so fragile that saying its name breaks it?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

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

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

Can you find the thief by just looking at the picture below?