When is added to dissolved in

CHEMISTRY · Single correct · A Level · Chemistry · Transition metals and their chemistry · Transition metals and their chemistry

Problem

When Zn(s)\text{Zn}(\text{s}) is added to K2Cr2O7\text{K}_2\text{Cr}_2\text{O}_7 dissolved in HCl(aq)\text{HCl}(\text{aq}), the colour of the solution changes from orange to green, then to blue and, over time, back to green. Formation of the green colour on addition of zinc is due to (a) Zn2+\text{Zn}^{2+} ion (b) CrO42−\text{CrO}_4^{2-} ion (c) Cr3+\text{Cr}^{3+} ion (d) Cr2+\text{Cr}^{2+} ion

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