Rank HCl, H2O2, H2, and HgCl2 in order of decreasing boiling point
HCl > H2O2 > HgCl2 > H2
The boiling point of a substance depends on several factors, including intermolecular forces, molecular size, and polarity.
HCl (hydrochloric acid) is a polar molecule with hydrogen bonding and dipole-dipole interactions. These strong intermolecular forces result in a relatively high boiling point.
H2O2 (hydrogen peroxide) is also a polar molecule with hydrogen bonding and dipole-dipole interactions. It has a slightly lower boiling point compared to HCl.
HgCl2 (mercury(II) chloride) is a compound composed of mercury and chlorine atoms. It has weaker intermolecular forces compared to HCl and H2O2, resulting in a lower boiling point.
H2 (hydrogen gas) is a nonpolar molecule with weak intermolecular forces (dispersion forces). It has the lowest boiling point among the given substances due to its small molecular size and lack of polarity.