Identify in which of the following case can the average molecular mass of the mixture be 150 at same instant in a reaction

Options

A. `N_(2(g)) + 3H_(2(g)) to 2NH_(3(g))`
B. `PCl_(3(g))+Cl_(2(g))to PCl_(5(g))`
C. `H_(2(g))+1/2O_(2(g))to H_(2)O_((g))`
D. `H_(2(g))+Cl_(2(g)) to 2HCl_((g))`

Explanation

Because only in this case there are gases having molar mass greater than 150