Which tank will fill first?

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

What you cannot hold but it is yours?

What is the next shape from answers A, B, C, and D figure?

Who is that with a neck and no head, two arms and no hands? What is it?

ENEMY = 2 * LINK
LINK + 2 = HELL

Then what will be TAXI + HELL? Select from the options below:
a) ROTTEN
b) DANGER
c) HEAVEN
4) MORTAL

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

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?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?