Who can jump higher than a Mountain?

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

In the picture that is attached with this question, you can find a square which comprises of four little squares inside it. Consider this square to be made with matchsticks. You have to remove two matchsticks such that only two squares remain instead of five.How will you do it ?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

What makes this number unique: 8,549,176,320?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

People make me, save me, change me, raise me. What am I?

The barber of Town shaves all men living in the town. No man living in the town is allowed to shave himself. The barber lives in that town. Who then shaves the barber of the town?