Consider the following statements about manganate and permanganate ions. Identify the correct statements.
A. The geometry of both manganate and permanganate ions is tetrahedral
B. The oxidation states of Mn in manganate and permanganate are + 7 and + 6, respectively.
C. Oxidation of Mn(II) salt by peroxodisulphate gives manganate ion as the final product.
D. Manganate ion is paramagnetic and permanganate ions is diamagnetic.
E. Acidified permanganate ion reduces oxalate, nitrite and iodide ions.
Choose the correct answer from the options given below :

Approach: Evaluate each statement about manganate ($$MnO_4^{2-}$$) and permanganate ($$MnO_4^-$$) ions.

Statement A: Both manganate and permanganate ions are tetrahedral.

Both $$MnO_4^{2-}$$ and $$MnO_4^-$$ have Mn bonded to 4 oxygen atoms with no lone pairs on Mn. The geometry is tetrahedral for both. Statement A is correct.

Statement B: Oxidation states of Mn in manganate and permanganate are +7 and +6, respectively.

In $$MnO_4^{2-}$$: $$x + 4(-2) = -2 \implies x = +6$$. In $$MnO_4^-$$: $$x + 4(-2) = -1 \implies x = +7$$. So manganate has Mn in +6 and permanganate has Mn in +7, which is the reverse of what is stated. Statement B is incorrect.

Statement C: Oxidation of Mn(II) salt by peroxodisulphate gives manganate ion as the final product.

Peroxodisulphate ($$S_2O_8^{2-}$$) is a powerful oxidising agent. The oxidation of Mn(II) by peroxodisulphate actually gives permanganate ($$MnO_4^-$$), not manganate. Statement C is incorrect.

Statement D: Manganate ion is paramagnetic and permanganate ion is diamagnetic.

$$MnO_4^{2-}$$ (Mn in +6, $$d^1$$) has 1 unpaired electron, so it is paramagnetic. $$MnO_4^-$$ (Mn in +7, $$d^0$$) has no unpaired electrons, so it is diamagnetic. Statement D is correct.

Statement E: Acidified permanganate reduces oxalate, nitrite, and iodide ions.

Permanganate is an oxidising agent; it oxidises these species, not reduces them. The statement incorrectly says "reduces." Statement E is incorrect.

Correct statements: A and D only, which corresponds to Option 1.