Question

Volatile metals like ${\text{Zn,Cd}}$ and ${\text{Hg}}$ are purified by:
A.Liquidation
B.Distillation
C.Cupellation
D.Electrolysis

Answer 1

To answer this question you should recall the concept of bonding in these metals. Chemical Bonding is a process where there is a formation of a bond between two or more atoms, molecules, or ions to give rise to a new chemical compound. The type of bonding helps determine the boiling point hence the volatile nature of a compound

Complete step by step answer:
These elements are with ${{\text{d}}^{10}}$ configuration. Only metallic bonds exist in these cases. Whereas in other transition metals, in addition to metallic bonding caused by outer shell electrons, there is covalent bonding too due to incompletely filled d orbital. This results in a strong bond in other transition elements. Metallic bond being a weak bond, energy of atomization is less making these elements volatile.
For volatile compounds distillation is used. The process of distillation refers to the selective boiling and subsequent condensation of a component in a liquid mixture. It has been used as a separation technique in industries to either increase the concentration of a particular component in the mixture or to obtain pure components from the mixture. The process of distillation is based on the principle of difference in the boiling points of the components in the liquid mixture and acts by forcing one of them into a gaseous state.

Hence option B is correct.

Note:
In ideal cases, it can be said that any bond is hundred percent ionic or covalent. But in reality, any bond shows partial ionic and covalent character. The components of any molecular: the cations polarize the anions and try to pull the electronic charge towards themselves and this increases the electric charge between the two ions. This is the case with a covalent bond, that is an electron charge density is built up around the nuclei. Fajan’s rule is based on the fact that:Smaller the size of cation, larger the size of the anion will result in a more covalent character of the ionic bond.
More the charge density of cation, greater is the covalent character of the ionic bond.
Electronic configuration: For cations with same charge and size, the one, with $\left( {n - 1} \right){d^{n\;}}n{s^o}\;$ which is found in transition elements have greater covalent character than the cation with $n{s^{2\;}}n{p^6}\;$ electronic configuration, generally present s- block elements.