Why Wine Glass Stem is so long?

What does below Rebus say?

XLR8

2, 3, 5, 9, 17, _ What is the next number in the sequence?

Forwards I am heavy, backward I am not. What am I?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

I have Rs.50 and I spend it in the way as below.

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 ?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

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