Which of the following gases has a density of 0.715g/L at STP

a) He

b) CO2

c) CO

d) CH4

CO2 is the gas which has high density of 0.715/L at STP.

Explanation:

PV=nRT

at STP,

P, T=constant

V=Km/M

1/K=m/V*1/M=S*1/M

therefore,

The molar mass is more, as well as the density is also greater

Hence Only CO2 has greater mass and greater density.