Photochromic glass, which is used in sunglasses, turns darker when it is exposed to intense light and becomes clearer again when the light intensity decreases. The degree of darkening depends on the concentration of silver atoms. The reactions below are involved. Reaction 1: $\text{Ag}^+ + \text{Cl}^- \rightleftharpoons \text{Ag} + \text{Cl}$ Reaction 2: $\text{Cu}^+ + \text{Cl} \rightarrow \text{Cu}^{2+} + \text{Cl}^-$ Reaction 3: $\text{Cu}^{2+} + \text{Ag} \rightarrow \text{Cu}^+ + \text{Ag}^+$ Which statement about these reactions is correct?
- A$\text{Cu}^+$ and $\text{Cu}^{2+}$ ions act as catalysts.
- B$\text{Cu}^+$ ions act as an oxidising agent in reaction 2.
- CReaction 3 increases the darkness of the glass.
- DSilver atoms are reduced in reaction 3.