If the pressure of each gas is increased at constant temp until condensation occurs, which gas will condense at the lowest pressure?

there are 3 gases: methane, ethane, and butane. (formula, molar mass, temperature, and pressure given)

Butane

Explanation:

The only inter molecular attractions present between hydrocarbons is weak london dispersion forces. These forces are size dependent. More the surface area more the attractions.

Out of given gases butane is the highest member with greatest surface area among methane, ethane and itself.

So it will have higher intermoelcular london dispersion forces.

This makes it to condense easily at lower pressure as compared to methane and ethane.