Define mole in terms of mass.

Why is the statement ' $1$ mole of hydrogen' not correct? What should be the correct statement?

Define the following term:

Moles in terms of mass.

Define the following term:

Moles in terms of number.

How are the number of moles $\left(\mathrm{n}\right)$ of a substance calculated from its mass $\left(\mathrm{m}\right)$?

How is the number of moles$\left(\mathrm{n}\right)$ of a substance calculated from its number of molecules $\left(\mathrm{N}\right)$?