What is the change in oxidation number of $\mathrm{Cr}$ in the following redox reaction?

What is the change in oxidation number of $\mathrm{Cr}$ in the following redox reaction?

1. +2 to +3
2. -2 to +3
3. +7 to +3
4. +6 to +3

Asked in: MHT CET 2023 (12 May Shift 2)

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