What does this rebus puzzle means ?

You can hear me, but you can't touch or see me.

What am I?

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

At a party, there are five people and a whole round cake lying at the centre of the table. Only four people will make a cut and take their piece and the last one will get the remaining piece on the table. How can they make sure that everyone gets a 1/5th of the piece?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

What am I?

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

What word is pronounced the same if you take away four of its five letters?