Calculate the molecular formula for the following:

Calculate the molecular formula for the following:

A: empirical formula CH, molar mass = 78 g/mol

B: empirical formula NO2, molar mass = 92.02 g/mol

C: 49.5 g C, 5.15 g H, 28.9 g N, 16.5 g O by mass, molar mass = 195 g.

I need to see how to do it.

A] find the "molar mass" of the empirical formula, CH, which is 13. Since you have 78g/mol, then you need to multiply CH by 78/13 = 6 to get C6H6 aka benzene

B] NO2 MM = 14 + 2*16 = 46
92/46 = 2
N2O4

C] 49.5 g C, 5.15 g H, 28.9 g N, 16.5 g O by mass, molar mass = 195 g.
First, you need to divide each element's mass by the atomic mass to get on a mole basis
With luck you would have gotten integers, but it doesn't look like you will, so you will have to find a number to multiply them all by to get integers
C 49.5/12 = 4.125
H 5.15/1 = 5.15
N 28.9/14 = 2.064
O 16.5/16 = 1.031
So multiply them all by 1/1.031 [and use the exact masses, not the integers I am using]
To get something like
C4H5N2O
Now tot up it's molar mass:
48 + 5 + 28 + 16 = 97
195/97 = 2
So you have C8H10N4O2