Question:
An excess of potassium ions makes KCl crystals appear violet or lilac in colour
since ________.
(i) some of the anionic sites are occupied by an unpaired electron.
(ii) some of the anionic sites are occupied by a pair of electrons.
(iii) there are vacancies at some anionic sites.
(iv) F-centres are created which impart colour to the crystals.
Solution:
Option (i) and (iv) are the answers.