The empirical formula of an organic compound containing C and H is CH2. The mass of one liter of this organic gas is exactly equal to that of one...

The molecular formula is a multiple of the empirical formula of a compound. In other words,

molecular formula = n(empirical formula) 

where, n could be any whole number equal to or greater than 1. 

For example, the organic compounds C2H4, C3H6, C4H8, etc. all have the same empirical formula. In these cases, the value of n is 2, 3 and 4 respectively.

In the current case, the mass of 1 l of organic compound is same as that of 1 l of nitrogen gas (N2), at the same temperature and pressure. Using the ideal gas law:

PV = nRT

or, n  = PV/RT

at the same temperature and pressure, the same volume of gases (1 l each) will have the same number of moles.

This also means that the molar mass of organic compound is equal to that of nitrogen gas, which is equal to 28 g.

The empirical formula mass = number of carbon atoms x atomic mass of carbon + number of hydrogen atoms x atomic mass of hydrogen 

 = 1 x 12 + 2 x 1 = 14

Molecular mass = n x empirical formula mass

or, n = molecular mass / empirical formula mass = 28 / 14 = 2

Thus, the molecular formula = 2 (CH2) = C2H4.

Thus, the organic compound is 'C_2H_4,' also known as ethylene or ethene.