When we see 2 but call 10?

What is the end of everything?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Christina is older than Kareena and Karishma. Katrina is older than Karishma and younger than Kareena. If Kareena has a brother named John, who is older than Christina, who's the youngest?

Two natural numbers have a sum of less than 100 and are greater than one.

John knows the product of the numbers and Jacob knows the sum of numbers.

The following conversation takes place between them:
John: 'I am not aware of those numbers.'
Jacob: 'I knew you wouldn't be. I am not aware myself.'
John: 'Now I know them!'
Jacob: 'Now I know them, too!'

What are the two numbers?

What is next number in the pattern below:

131 517 192 123 ?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?

How is a fly different from a mosquito?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?