Other chlorides are not volatile enough to form CrO₂CI₂.

The correct answer is: BaCI₂

High energies of ionization and low heats of hydration of their ions and high heats of sublimation are the reason behind less tendency to form cations as compared to elements of I, II and III A groups.

The correct answer is: all

FeSO₄ 7H₂O is oxidised by oxygen of air and hence its composition changes with time.
4FeSO₄ + 2H₂O + O₂ → 4 Fe (OH)SO₄

The correct answer is: FeSO₄.7H₂O

KNO₃ is added to oxidise the lead and zinc impurities.

The correct answer is: to oxidise the impurities of lead and zinc present in it

Stirring is needed for reduction of Au (III) in AuCI₄^- at the electrode.

The correct answer is: for overcoming the repulsive forces between the AuCl₄^- and excess electrons at the electrode so as to help the deposition of Au (III)

The reason for existence of mercury metal in liquid state even at 0°C is its very high ionisation energy and presence of weak metallic bond because of absence of unpaired electrons.

The correct answer is: mercury has high ionisation energy and posseses weak metallic bond

Cr₂O₃.2H₂O is known as Guigret's green.

The correct answer is: Cr₂O₃.2H₂O

Assertion is wrong. Reason is correct. The orange colour of K₂Cr₂O₇ is due to Cr₂O₇^2- ions.

The correct answer is: Both Statement-1 and Statement-2 are true and Statement-2 is the correct explanation of Statement-1.

Given all statements are correct.

The correct answer is: Transition metals have high enthalpies of sublimation, The atomic sizes of third series of transition metals are not very much different from those of second series in respective groups, Most of the transition metals of first series have negative reduction potentials and hence react readily with dilute acids to liberate H₂, Cr, Mo and W are very hard metals because of greater number of covalent bonds involving unpaired electrons.