The correct option is D Charge and size of the ions
Factor affecting electrolytic conductance/resistance:
(a) Solute- Solute interaction:
When inter–ionic force of attraction between solute is higher, the resistance will be higher. Thus, lower will be the conductance.
Attractive force ∝Charge of ions
At higher concentration, the force of attraction between the ions increases which decreases the speed of the ions. Hence, conductance decreases with increase in concentration.
(b) Solute - solvent interaction:
It is an interaction of a solute with the solvent. It restricts the free motion of ions, thus, decreasing conductance. It is actually the solvation/ hydration of ions.
Greater the solvation, greater will be the resistance.
Solvation∝Change on ions∝1Size
Smaller the size of ions, greater will be the solvation. Thus, the resistance will be higher and conductance will be lower.
On dilution, the solute - solvent interactions decrease. Thus, the ionic mobility and conductance increases.
(c) Nature of electrolyte:
Weak electrolyte will have high resistance and low conductance becuase they do not undergo complete dissociation.
Strong electrolyte will have low resistance and high conductance becuase they undergo complete dissociation.
Thus, all the given factors will determine the electrolytic conductance of a solution.