Compare the volume of 14.1 g of helium to 14.1 g of argon gas (under identical conditions).

The Volumes can be calculated from Masses by using following Formula,

                                        Density  =  Mass / Volume
Solving for Volume,
                                        Volume  =  Mass / Density

Mass of Both Gases  =  14.1 g

Density of Argon at S.T.P  =  1.784 g/L

Density of Helium at S.T.P  =  0.179 g/L

For Argon:
                                        Volume  =  14.1 g / 1.784 g/L

                                        Volume  =  7.90 L

For Helium:
                                        Volume  =  14.1 g / 0.179 g/L

                                        Volume  =  78.77 L