Step 1: Geometry.
Both MnO4 2− (manganate) and MnO4 − (permanganate) have tetrahedral geometry.
So, statement A is correct.
Step 2: Oxidation states.
In MnO4 2−, manganese oxidation state is +6.
In MnO4 −, manganese oxidation state is +7.
Statement B is correct.
Step 3: Oxidation by peroxodisulphate.
Mn(II) salts oxidize to permanganate, not manganate.
So, statement C is false.
Step 4: Magnetic properties.
Manganate ion (Mn +6) has d1 electronic configuration and is paramagnetic.
Permanganate ion (Mn +7) has d0 electronic configuration and is diamagnetic.
So, statement D is correct.
Step 5: Redox properties.
Acidified permanganate ion is a strong oxidizing agent and oxidizes oxalate, nitrite, and iodide ions.
So, statement E is correct.
Correct statements:
A, B and E
Therefore, option (4) is correct.