Chemistry (M.Phil./Ph.D.) 2016 Panjab University Entrance Exam With Answers

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18.

The self indicating silica gel (impregnated with cobalt chloride) turns pink on absorbing moisture and becomes blue on heating. The pink and blue colour are respectively due to

A: [Co(H2O)6]2+ and [CoCl4]2-
B: [Co(H2O)6]2+ and Co2O3
C: [Co(H2O)6]2+ and [Co(H2O)6]3+
D: Co2+ and Co3+

The answer is: A