Why Is Calcium Fluoride,Ca $\mathrm { F } _ { 2 }$

Multiple Choice

Why is calcium fluoride,Ca $\mathrm { F } _ { 2 }$ ,a high melting point crystalline solid while stannic chloride, $\mathrm { SnCl } _ { 4 }$ ,is a volatile liquid?

A) There is no theory to predict the physical property of melting point.Melting point temperatures are empirically determined.
B) Actually,we would predict these results to be the opposite.Since each metal is combined with a group 17 halogen,the heavier metal (tin) combination should have the higher melting point.
C) Ca $\mathrm { F } _ { 2 }$ is a small,linear,non-polar molecule,while $\mathrm { SnCl } _ { 4 }$ is a huge tetrahedral structure.Therefore the bonds in calcium fluoride tend to give it a higher melting point temperature.
D) Ionic compounds formed by elements on opposite sides of the periodic table,like $\mathrm { CaF } _ { 2 }$ ,tend to have higher melting points than more covalently bonded structures,like $\mathrm { SnCl } _ { 4 }$