Answer : The chemical formula for the compound is, 
Explanation :
When the element 'M' react with the
to give
.
The balanced chemical reaction is,

In this reaction, 'M' is in mono-atomic form and
is in diatomic form.
By the stoichiometry,
2 moles 'M' react with the 1 mole of
to give 2 moles of
.
Therefore, the chemical formula of the compound is, 
Molar mass is the mass of one stable molecule of a compound, that cannot join with another molecule of the same kind to form a new one, while an empirical formula is the molecular formula in its simplest form. E.g. empirical formula of ethene is CH2while its molecular formula is C2H4.
Answer:
Oxygen = 15.999 g/mol
Iron = 3 × 55.845 = 167.535 g/mol
CaCO3 = 20 × 100.0869 = 2001.738 g/mol
Answer:
C
Explanation:
I'm assuming that you meant to type neutral charge.
Since electrons are negative and protons are positive, having a balanced number of both of these would cause an atom to have a neutral charge.