Which of the following aquated metal ions has the highest paramagnetism? — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: Spin-only magnetic moment is directly proportional to the number of unpaired d-electrons (n) according to the formula μ = \sqrt{n(n+2)} BM. Step 2: Analyze each ion: Cr^3+ (3d^3) has 3 unpaired electrons; Fe^2+ (3d^6, high-spin with weak ligand H2O) has 4 unpaired electrons; Cu^2+ (3d^9) has 1 unpaired electron; Zn^2+ (3d^10) has 0 unpaired electrons. Step 3: Since Fe^2+ possesses the highest number of unpaired electrons (n = 4), it exhibits the highest magnetism, matching option (b).