In which one of the following, does the given amount of chlorine exert the least pressure in a vessel of capacity \(1 \mathrm{dm}^{3}\) at \(273 \mathrm{~K}\) ?

Ideal gas equation is
\[
\mathrm{pV}=\mathrm{nRT}
\]
When \(\mathrm{V}\) and \(\mathrm{T}\) are same,
\[
\mathrm{p} \propto \mathrm{n}
\]
Thus, when number of moles, ie, \(\mathrm{n}\) is least, it will exert least pressure.
(a) \(\mathrm{n}=\frac{\mathrm{wt}}{\mathrm{mol} \text {. wt }}=\frac{0.0355}{35.5}=1 \times 10^{-3} \mathrm{~mol}\)
(b) \(\mathrm{n}=\frac{0.071}{35.5}=2 \times 10^{-3} \mathrm{~mol}\)
(c) \(\mathrm{n}=\frac{\text { number of molecules }}{\mathrm{N}_{\mathrm{A}}}\) \(=\frac{6.023 \times 10^{21}}{6.023 \times 10^{23}}=0.01 \mathrm{~mol}\)
(d) \(\mathrm{n}=0.02 \mathrm{~mol}\)
Thus, \(0.0355 \mathrm{~g}\) chlorine will exert the least pressure.