Below are 5 sets of potential solutes for you to compare. Both members of each pair are very soluble in water. If you had equal molar concentrations of each solution, which member of each pair would theoretically be the better conductor of electricity? A. CsCl, CaCl2.
B. CaS, Li2S.
C. KBr, AlCl3.
D. AlCl3, MgC2.
E. KI, K2S.

Option D. AlCl₃, MgC₂

Explanation:

We need to dissociate all the salts, to determine the i. (Van't Hoff factor).

The salt who has the highest value, will be the better conductor of electricity

CsCl  → Cs⁺  +  Cl⁻   i = 2

CaCl → Ca²⁺ +  Cl⁻   i = 2

CaS → Ca²⁺ +  S⁻²    i = 2

Li₂S → 2Li⁺  +  S⁻²    i = 3

KBr →  K⁺  +  Br⁻       i = 2

AlCl₃ →  Al³⁺ + 3Cl⁻   i = 4

MgC₂  →  Mg²⁺  +  2C⁻   i = 3

KI  →  K⁺  +  I⁻     i = 2

K₂S  →  2K⁺  + S⁻²   i = 3

The biggest i, is in pair D.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.