Question

A metal forms chloride in its $ + 2$ and $ + 4$ oxidation states. Which of the following statements about these chlorides is correct?
A.$\text{MC}{{\text{l}}_{\text{2}}}$ is more ionic than$\text{MC}{{\text{l}}_{4}}$
B.$\text{MC}{{\text{l}}_{\text{2}}}$ is more easily hydrolysed than$\text{MC}{{\text{l}}_{4}}$
C.$\text{MC}{{\text{l}}_{\text{2}}}$ is more volatile than$\text{MC}{{\text{l}}_{4}}$
D.$\text{MC}{{\text{l}}_{\text{2}}}$ is more soluble in anhydrous ethanol than $\text{MC}{{\text{l}}_{4}}$

Answer 1

Hint: The nature of a compound whether it will be ionic or covalent depends a lot of the oxidation state of the cation and this is guided by the Fajan’s Law which states that if a cation has low positive charge than it will be ionic while if the cation has high positive charge then it will be covalent.

Complete answer:
The Fajan’s Law states it is applicable to cations and predicts the nature of the compounds that they form depending upon the size, charge, and the electronic configuration of the cation. It predicts that cations with small size, high charge and the presence of large anions leads to the formation of covalent compounds, while cations with large size, small charge and the presence of small cations leads to the formation of ionic compounds.
Hence it can be said that $\text{MC}{{\text{l}}_{\text{2}}}$ should be more ionic than $\text{MC}{{\text{l}}_{4}}$, due to the higher ionic character of$\text{MC}{{\text{l}}_{\text{2}}}$ than $\text{MC}{{\text{l}}_{4}}$.

Therefore, the correct option among the above options is option A.
Note:
An example of the Fajan’s Rule is as follows: an aluminium ion has a tripositive charge and a small size, now two contrasting cases are that aluminium iodide has an ionic bond with covalent character. The high positive charge on the aluminium ions pulls away the charge from the anions. If we see the iodide anion then the large size of the anion and the electrons in the valence shell are well shielded from the nuclear charge and this helps the aluminium ion to pull off the electron cloud from the anion. This gives the ionic compound with covalent character.