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

Can you find out the number that should replace the question mark with a valid reason?

What number when divided in half becomes zero?

What is more useful when it is broken?

Can you find the key in the picture below?

How can you take 2 from 5 and leave 4?

Buy me, smell me or deliver me, I do not change.

Who am I?

In Greek mythology, the Sphinx sat outside of Thebes and asked this riddle of all travellers who passed by. If the traveller failed to solve the riddle, then the Sphinx killed him/her. And if the traveller answered the riddle correctly, then the Sphinx would destroy herself. The riddle:

What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Oedipus solved the riddle, and the Sphinx destroyed herself.

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

What does this rebus picture identify?