Question

Assertion: In the series $ Sc $ to $ Zn $ , the enthalpy of atomization of zinc is the lowest.
Reason: Zinc has a greater number of unpaired electrons.
(A) Both reason and assertion are correct and reason is correct explanation for assertion
(B) Both reason and assertion are correct but reason is not correct explanation for assertion
(C) Assertion is correct but reason is incorrect
(D) Both the assertion and reason are incorrect

Answer 1

Hint: Zinc behaves like a $ p $ block element as its $ d $ shell is full and it only gives up its two electrons. The change in enthalpy when one mole of bonds is broken to obtain atoms in the gas phase is generally called the enthalpy of atomization.

Complete answer:
Zinc does not contain any unpaired electrons in the ground state as well as in its common oxidation state unlike the element scandium. Zinc is transition metal and remember that the enthalpy of atomization depends on the number of unpaired electrons and if the number of unpaired electrons is more, then the interatomic metallic bonding is stronger and also the enthalpy of atomization is higher.
Therefore, Option C is the correct answer.

Note:
As we move down the group in the periodic table, the bonds get stronger and more energy is required to break those bonds. The enthalpy is defined as the heat content of the given system at constant pressure. The heat which is absorbed or released by a chemical reaction at constant pressure is called the enthalpy change. The enthalpy of atomization is related to the strength of the metallic bonds that are associated with the number of unpaired electrons present in the valence shell of the element.