Can you convert the number zero(0) into a positive number using just one mathematical operator ?

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?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

What do you call a fish without an eye?

I am white when I am dirty, and black when I am clean. What am I?

A man is found dead in his bathroom naked with blood scattered all around him. The bathroom was locked from the inside and there is no trace of any struggle. There is nothing in the bathroom except his pant with the belt still around and his shirt. Also, the medic team can't find any incision in his body that may have been the reason behind so much blood loss.

The Police department is clueless regarding this murder mystery.
Can you?

I cannot talk, but I always reply when spoken to. What am I?

Decode this picture on T-Shirt and tell what it says ?