Question

which of the following molecules likely has the lowest boiling point?
i₂
h₂
br₂
o₂

Explanation:

The boiling point of non - polar covalent molecules (such as \(I_2\), \(H_2\), \(Br_2\), \(O_2\)) is mainly determined by the strength of London dispersion forces. London dispersion forces increase with the increase of molecular mass. Calculate the molecular masses: \(M(I_2)=2\times126.9 = 253.8\space g/mol\), \(M(H_2)=2\times1.008 = 2.016\space g/mol\), \(M(Br_2)=2\times79.904 = 159.808\space g/mol\), \(M(O_2)=2\times16.00 = 32.00\space g/mol\). Since \(H_2\) has the smallest molecular mass among them, it has the weakest London dispersion forces.

Answer:

\(H_2\)