Question

a gas has a density of 1.98 g/L at standard temperature and pressure what is the molar mass

Answer 1

At STP molar volume is

$V_m = 22.4 dm^3/mol$

$density = \frac{M}{V_m}$

$M = density\times V_m = 1.98 \frac{g}{L}\times 22.4 \frac{L}{mol}= 44.4 \frac{g}{mol}$