Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes:

Isotope	Isotopic molar mass $(g \, mol^{-1})$	Abundance (%)
$^{36}Ar$	$35.96755$	$0.337$
$^{38}Ar$	$37.96272$	$0.063$
$^{40}Ar$	$39.9624$	$99.600$

(N/A) The molar mass of an element with multiple isotopes is calculated by the weighted average of the isotopic masses:
$\text{Molar mass} = \sum (\text{Isotopic mass} \times \text{Fractional abundance})$
$\text{Molar mass} = \left[ \left( 35.96755 \times \frac{0.337}{100} \right) + \left( 37.96272 \times \frac{0.063}{100} \right) + \left( 39.9624 \times \frac{99.600}{100} \right) \right] \, g \, mol^{-1}$
$= [0.12121 + 0.02392 + 39.80255] \, g \, mol^{-1}$
$= 39.94768 \, g \, mol^{-1}$
Rounding to appropriate significant figures,the molar mass is $39.948 \, g \, mol^{-1}$.