(a) Using the expression Ka=[H+][A−][HA] , explain how to determine which solution has the lower pH , 0.10MHF(aq) or 0.10MHC2H3O2(aq) . Do not perform any numerical calculations.

Ka=[H+][A−]/[HA]

which solution has the lower pH, 0.10MHF(aq) or 0.10MHC2H3O2(aq) :

Higher value of Ka indicates greater ionization thus more protons in solution, higher H+ concentration in solution means lower pH value.

Since HF have higher Ka have, thus HF solution will have lower pH.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

the answers would be

the first one and the second one