An acidified solution of potassium permanganate is treated with an excess of oxalic acid. The spin-only magnetic moment of the manganese-containing product formed in this reaction is closest to:

Step-by-step solution

In an acidic medium, potassium permanganate ( KMnO ₄ ) oxidises oxalic acid ( H ₂ C ₂ O ₄ ) to carbon dioxide and is itself reduced to the manganese(II) ion ( Mn ²⁺ ). The reaction is: 2 MnO ₄^- + 5 H ₂ C ₂ O ₄ + 6 H ^+ 2 Mn ²⁺ + 10 CO ₂ + 8 H ₂ O The manganese-containing product is Mn ²⁺ . The atomic number of Mn is 25, so its ground state electronic configuration is [ Ar ] 3 d ^5 4 s ^2 . For the Mn ²⁺ ion, the configuration is [ Ar ] 3 d ^5 . This gives n = 5 unpaired electrons. The spin-only magnetic moment is