A compound with the empirical formula NPCl2 was found in a subsequent experiment to have a molar mass of 347.64 g/mol. What is the molecular formula of the compound?

                     Molecular Formula  =  N₃P₃Cl₆

Explanation:

Molecular formula is calculated by using following formula,

                    Molecular Formula  =  n × Empirical Formula   (1)

Also, n is given as,

                     n  =  Molecular Weight / Empirical Formula Weight

Molecular Weight  =  347.64 g.mol⁻¹

Empirical Formula Weight  =  1 (N) + 1 (P) + 2 (Cl)  =  115.88 g.mol⁻¹

So,

                     n  =  347.64 g.mol⁻¹ ÷ 115.88 g.mol⁻¹

                     n  =  3

Putting Empirical Formula and value of "n" in equation 1,

                    Molecular Formula  = 3 × NPCl₂

                    Molecular Formula  =  N₃P₃Cl₆

the answer would be c