What is the Surname of Barbie Doll?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?

Can you tell a 3D object that has just two surfaces?

How many times in a given day, minutes and hour clock comes in a straight line ?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

What can you catch but never throw?

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?