The reaction between aqueous iron(III) ions, $\text{Fe}^{3+}$(aq), and aqueous thiocyanate ions, $\text{SCN}^-$(aq), is reversible. Its equation is $\text{Fe}^{3+}(aq) + \text{SCN}^-(aq) \rightleftharpoons \text{FeSCN}^{2+}(aq)$. When equilibrium is reached, the concentrations of $\text{Fe}^{3+}$ ions, $\text{SCN}^-$ ions, and $\text{FeSCN}^{2+}$ ions are identical, and the mixture is orange in colour. If a few drops of aqueous thiocyanate ions are then added to the mixture, a new equilibrium is established. How does the colour of the mixture change?
- AIt becomes colourless.
- BIt becomes a lighter orange.
- CIt becomes more yellow.
- DIt becomes more red.