Solubility rules for copper(II) compounds

Steps:

• Recall solubility rules: nitrates are always soluble; carbonates, oxides, and hydroxides of transition metals like copper are generally insoluble.
• Check option A: copper(II) carbonate (CuCO₃) follows the rule for insoluble carbonates.
• Check options B and C: copper(II) oxide (CuO) and hydroxide (Cu(OH)₂) are basic oxides/hydroxides, insoluble in water.
• Check option D: copper(II) nitrate (Cu(NO₃)₂) is a nitrate salt, which is soluble.

Why D is correct:

• All nitrate salts are soluble in water per standard solubility rules.

Why the others are wrong:

• A: Carbonates of copper (transition metal) are insoluble.
• B: Copper(II) oxide is insoluble as a metal oxide.
• C: Copper(II) hydroxide is insoluble as a metal hydroxide.

Final answer: D