How do you compare the boiling points of SiH4 PH3 H2S and HCl?

The boiling point of SiH4: -111.7 °C

The boiling point of PH3: -87.7 °C

The boiling point of H2S: -60 °C

The boiling point of HCl: -85.05 °C

Now that you have all the boiling points you can make a comparison between them.

The boiling points of substances made up of discrete molecules depends on the strengths of the intermolecular forces.

H2S …….. -60C ……………. polar ………… bent molecular geometry
HCl ……… -85.1C …………. polar ………… linear
PH3 …….. -87.7C …………. polar ………… trigonal pyramidal
SiH4 ……. -111.7C ………. nonpolar …… tetrahedral

The polar molecules exhibit Keesom forces (dipole-dipole attraction) as well as Debye forces and London dispersion forces. SiH4 is nonpolar, and exhibits only London forces which accounts for the much lower boiling point