What does below chemistry rebus means?

I add 5 to 9 and get 2. The answer is correct, so what am I?

A king sentenced a man to the death sentence for some crime he had committed. Known for his kindness, the king told the culprit that he had a choice to die in a way he decides.

The culprit was clever and said something that saved him from death. What method do you think he must have chosen for his death?

Which alphabet is a part of our body?

Solve below rebus puzzle?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

When is the top of a mountain similar to a savings account?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?