A transition metal ion, $M^{2+}$, is oxidised by acidified dichromate(VI) ions to produce $M^{4+}$ ions, $\text{Cr}^{3+}$ ions and $\text{H}_2\text{O}$. Which equation shows this reaction correctly?
- A$\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + \text{M}^{2+} \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O} + \text{M}^{4+}$
- B$\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + 2\text{M}^{2+} \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O} + 2\text{M}^{4+}$
- C$\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + 3\text{M}^{2+} \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O} + 3\text{M}^{4+}$
- D$\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + 6\text{M}^{2+} \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O} + 6\text{M}^{4+}$