How to calculate the molicular mass of any atom

Q. One mole is defined as:

Q. How to calculate relative molecular mass?

Q. (a) Calculate the gram molecular mass of water from the values of gram atomic mass of hydrogen and of oxygen.
Gram atomic mass of hydrogen $=1g$
Gram atomic mass of oxygen $=16g$
(b) Atoms and molecules are the building blocks of matter. List out any three differences between them.

Q. (a) Calculate the gram molecular mass of water from the values of gram atomic mass of hydrogen and oxygen.
Gram atomic mass of hydrogen $=1g$
Gram atomic mass of oxygen $=16g$
(b) Modern atomic theory takes up the wave concept, principles of uncertainity and other latest discoveries to give a clear-cut picture about an atom. State any three findings of modern atomic theory.