JEE Main2014ChemistrySolid StateActual

The appearance of colour in solid alkali metal halides is generally due to:

Options

ASchottky defect
BFrenkel defect
CInterstitial position
DF-centres

Correct answer

D. F-centres

Step-by-step solution

The appearance of colour in alkali metal halides is generally due to F-centres. F centers in NaCl produce a band of optical absorption towards the blue end of visible spectrum, thus the colour appears yellow under transmitted light. On the other hand, KCl with F -centers appears magenta, and KBr appears blue.

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