Before Mount Everest was discovered, what was the highest mountain in the world?

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?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

What word is represented by this rebus?

Can you solve below mathematical equation?

2^1234 - 2^1233

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

There are forty elephants and they have forty-fore heads. How can this be possible?

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

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

In a jungle where there are no street lights or any other artificial source of lights, I notice a black snake crossing the road.
How did I get sight of the snake?