2n+3h2 gives 2nh3 find out the total number of molecules and atoms

Answer 1

Do you mean
N2 + 3H2 = 2NH3 ?
each group of atoms is a molecule, right?
so, count the atoms, and count the groups
Maybe some parentheses would help distinguish
(N2) + 3(H2) = 2(NH3)

Answer 2

With no percentages and no masses given I don't have a clue as to how you determine the number of atoms or molecules. It just can't be done.

Answer 3

Nil