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

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

Who am I?

When can we add 2 to 11 and get 1 as the correct answer?

What is the fastest way to double your money?

Which city is three-fifths chick two third cat and 50% goat?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

What type of tree can I carry in my hand?

By what process could you make a 'Tea-Table' into food?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

What always comes into a house through the keyhole?