Question

Consider equal masses of the gasses bel0w. Which 0ne 0f these gasses w0uld 0ccupy the smallest v0lume at STP? A. N2 B. C02 C. CH4 D. S02

Answer 1

i believe it is sulfur dioxide. it has the strongest intermolecular forces of attraction (i.e permanent dipole-permanent-dipole) thus they would be more closely packed.

Answer 2

at same temp. and pressure, volume of gas occupied is directly proportional to no. of moles of the gas.

so, the gas with least number of moles for the given mass taken, will have the smallest volume.
and as
\[number of moles= \frac{ mass taken }{ molar mass of gas }\]

mass taken is constant, so, no. of moles varies inversely with respect to molar mass of gas.

so, the gas with highest molar mass, will have lowest no. of moles and hence, lowest volume for the given mass.
the ans. is SO2.. as @ezizio said.