Ammonium chloride, NH4Cl, is a white solid. When heated to 325C, it gives a vapor that is

Question:

Ammonium chloride, NH4Cl, is a white solid. When heated to 325C, it gives a vapor that is a mixture of ammonia and hydrogen chloride.
NH4Cl(s) → NH3(g) + HCl(g)
Suppose someone contends that the vapor consists of NH4Cl molecules rather than a mixture of NH3 and HCl. Could you decide between these alternative views on the basis of gas-density measurements? Explain.