Answer
$0.675\frac{g}{L}$
Work Step by Step
From ideal gas law
$n=\frac{PV}{RT}$
We plug in the known values to obtain:
$n=\frac{\frac{751}{760}\times 1}{0.08206\times 304}=0.03961mol$
Now $0.03961mol\times \frac{17.03g}{1mol}=0.675g$
Thus the density of ammonia is $0.675\frac{g}{L}$
