What does below chemistry rebus means?

If Rajina's daughter is my daughter's mom, who am I to Rajina?

John needs to purchase 100 chocolates from three different shops and he has exactly 100 rupees to do that which he must spend entirely. He must buy at least 1 Chocolate from each shop.

The first shop is selling each chocolate at 5 paise, the second is selling at 1 rupee and the third is selling at 5 rupees.

How many chocolates should he buy from each shop?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

Which five letter word can be added at the end of below word to form a
valid word?

> Pin
> Check
> Boiling
> View

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Decode below rebus
D
N
A
T
S , D

A man is found hanging dead from the ceiling of a room. The room’s dimensions are 15 x 15 x 15. The man is only 6ft tall and the rope was only 2ft long. There are no windows and only one door to the room. The door is bolted shut from the inside, and a puddle of water is under the man. How did he kill himself?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

Jigsaw captured 100 people and make them stand in a circle and all these people are labelled as Person1, Person2, Person3... Person100. He made them play a crazy game in which Person 1 shot Person 2 and pass the gun to the next person and so on until one stands alive.

Which person will survive in the end?