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

What is the word or phrase?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Who has married many women but was never married?

Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

It is a six-letter word.
The first four letters are me.
The second and last letters are the same.
The fourth second and last letter is payment.

Who is it?