Reactivity series positions of metals P, Q, R, S Steps:

• Examine the reactivity series diagram: S (most reactive, top), Q, R, P (least reactive, bottom).
• Test statement A: P at bottom confirms it as least reactive.
• Test statement B: Q above R means Q more reactive, so displaces R from its salt solution.
• Test statements C and D: Match positions to common metals like zinc (mid-series) and copper (low reactivity).

Why D is correct:

• S occupies the top position (most reactive), but copper is low in the series (below hydrogen), so S cannot be copper.

Why the others are wrong:

• A is correct: P is at the bottom, making it the least reactive metal.
• B is correct: Q is higher than R in the series, allowing displacement per the reactivity rule.
• C is correct: Zinc fits the mid-series position of R.

Final answer: D