How many times can you subtract the number two from the number fifty?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

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

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

There are four 3-link chains. All you have to do is join them into a big 12-link chain. For joining two closed links, one of the links must be cut and placed onto the other link for closing.

How many minimum links will you have to cut to make the big chain?

What does the following BrainBat signifies?

ABCDEFGHIJKLMNOPQRSTUVWYZ

QQQQQQQQQQQQQQQQQQQQQQQQQ.

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?

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?