I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

What does this rebus puzzle means ?

I know a nine-letter word having only one vowel.
Do you ?

If a wheel has 54 spokes, how many spaces are there between the spokes?

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

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

What work can one never finish?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?