Since Air Is a Mixture,it Does Not Have a "Molar

Multiple Choice

Since air is a mixture,it does not have a "molar mass." However,for calculation purposes,it is possible to speak of its "effective molar mass." (An effective molar mass is a weighted average of the molar masses of a mixture's components.) If air at STP has a density of 1.285 g/L,its effective molar mass is ________ g/mol.

A) 26.94
B) 31.49
C) 30.00
D) 34.42
E) 28.80