Which of the following is the correct decreasing order of the melting points of calcium halides?

Which of the following bonds is the most covalent?

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A :$ Lithium halides are somewhat covalent in nature.
Reason $R :$ Lithium possesses high polarization capability.
In the light of the above statements,choose the most appropriate answer from the options given below:

The covalent character of $CaCl_2, BaCl_2, SrCl_2$ and $MgCl_2$ follows the order:

How many of the following orders of covalent character are $TRUE$?
$(i)$ $LiF < LiCl < LiBr < LiI$ (Fajans' rule: covalent character increases with increasing size of anion)
$(ii)$ $CaCl_2 < FeCl_2 < FeCl_3$ (Fajans' rule: covalent character increases with increasing charge on cation)
$(iii)$ $Hg_2Cl_2 < HgCl_2$ (Fajans' rule: covalent character increases with increasing charge on cation)
$(iv)$ $ZnCl_2 < CdCl_2 < HgCl_2$ (Fajans' rule: covalent character increases with increasing polarizability of cation)
$(v)$ $CuCl < AgCl < AuCl$ (Fajans' rule: covalent character increases with increasing polarizability of cation)
$(vi)$ $AlN > Al_2O_3 > AlF_3$ (Fajans' rule: covalent character increases with increasing charge on anion)
$(vii)$ $CaF_2 < CaCl_2 < CaBr_2 < CaI_2$ (Fajans' rule: covalent character increases with increasing size of anion)

Polarisability of halide ions increases in the order: