Identifying metals via reactivity and solubility rules Steps:

• Metal reacts with water (likely steam for H2 gas), indicating high reactivity like magnesium.
• Zn displaces Y from salt solutions, placing Y below Zn in reactivity series (e.g., copper).
• Carbonate of Z insoluble, true for most non-alkali metals like copper (CuCO3 precipitates).
• Match options to fit all clues: reactive metal, Y below Zn, Z with insoluble carbonate.

Why B is correct:

• Option B assigns copper to Y (Zn + CuSO4 → ZnSO4 + Cu, per reactivity series) and copper to Z (CuCO3 insoluble in water).

Why the others are wrong:

• A: Magnesium as Y, but Mg above Zn in reactivity series, so no displacement.
• C: Lists sodium (reactive) but assigns magnesium to Z; however, doesn't fit unique B structure for Y/Z both copper.
• D: Sodium as Z, but Na2CO3 soluble, contradicting insolubility.

Final answer: B