Appearance of the violet or lilac in colour on the addition of the excess of potassium ions in the KCl crystal is because of :

Options

A. Some of the anionic sites are occupied by a unpaired of electrons.
B. Some of the anionic sites are occupied by a pair of electrons.
C. There are vacancies at some anionic sites
D. F-centres are created which impart colour to thee crystals

Answer

A, D