P = Iron (Fe); Q = Zinc (Zn)
The light green solution is FeSO₄ (ferrous sulphate), so metal P is Iron (Fe). The solution turns colourless after the reaction, forming ZnSO₄, so metal Q is Zinc (Zn).
Chemical equation:
$$\text{Zn}(s) + \text{FeSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Fe}(s)$$
Conclusion: Zinc is more reactive than iron. A more reactive metal displaces a less reactive metal from its salt solution.
Source: Chemical Reactions and Equations, Section 1.2.3 (Displacement Reaction)
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The key clues are: (1) light green colour of PSO₄ → FeSO₄ → P = Fe; (2) colourless product QSO₄ → ZnSO₄ → Q = Zn. The textbook directly gives the Zn + CuSO₄ example; this is the analogous reaction with FeSO₄. Examiners expect the balanced equation with state symbols and a one-line reactivity conclusion. Do not confuse P and Q — P is in solution, Q is the rod doing the displacing.