Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

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

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?

Count the number of times the letter "F" appears in the following paragraph:

FAY FRIED FIFTY POUNDS OF
SALTED FISH AND THREE POUNDS
OF DRY FENNEL FOR DINNER FOR
FORTY MEMBERS OF HER FATHER'S FAMILY.

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

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

If a wheel has 54 spokes, how many spaces are there between the spokes?

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

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?

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.