Why Aeroplane windows are round?

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

John has eleven friends. He has a bowl containing eleven apples. Now He wants to divide the eleven apples among his friends, in such a way that an apple should remain in his bowl.
How can He do it?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

In the Thar desert, 3 men found a big 24L Jar is full of water. Since there is a shortage of water so they decided to distribute the water among themselves such that they all have equal amounts of it. But they only have a 13L, a 5L and an 11-litre Jar.

How do they do it?

What word begins and ends with an E, but has only one letter?

How could a baby fall out of a twenty-story building onto the ground and live?

If eleven plus two equals one, what does nine plus five equal?

What is more useful when it is broken?

I organized a small get together at my home.
In the party , i have a barrel with some whiskey in it.

Suddenly Guest 1 say 'I bet this barrel of whiskey is more than half full'.
'No, it's less than half full' Guest 2 replied.

I don't have any measuring instrument and without removing whiskey from it , how can i determine which of the guest is right ?