Which number should replace the question mark?

What can go through glass without breaking it?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

What have one eye but still cannot see?

A father told his three sons he would die soon and he needed to decide which one of them to give his property to. He said, “Go to the market and buy something large enough to fill my bedroom, but small enough to fit in your pocket. From this, I will decide which of you is the wisest and worthy enough to inherit my land.” They all went to the market, and each came back with a different item. The father told his sons to come into his bedroom one at a time and try to fill up his bedroom with their items. The first son came in and put some pieces of cloth he bought and laid them across the room, but it barely covered the floor. The second son came in and laid some hay on the floor, but there was only enough to cover half the floor. The third son came in and showed his father what he bought. He wound up getting the property. What did the third son show his father?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

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?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?