The correct IUPAC name of K2MnO4 is:

🧠 Three IUPAC Updates Hidden Here

JEE 2024 names test the modern (post-2005) IUPAC conventions:

1. Oxide ligand is now "oxido", not "oxo".
2. Inside an anionic complex the metal still ends in -ate, but the metal stem is the standard name (manganate, not manganese).
3. The cation count ("dipotassium") is omitted in IUPAC names — only the metal's charge state matters.

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The species is $\mathrm{K_2MnO_4}$ — manganate(VI), four oxide ligands.

Oxidation state of Mn. $2(+1) + x + 4(-2) = 0 \Rightarrow x = +6$.

Ligand block. 4 × oxide → "tetraoxido".

Metal block. Anionic complex → "manganate", with (VI) appended.

Cation block. "Potassium" — no "di" prefix in modern IUPAC.

Stitch: Potassium tetraoxidomanganate(VI).

⚡ Three-Word Pattern

Anionic complex names always read: cation + ligand-prefix-metal + (oxidation state). For oxoanions: $\mathrm{K_2CrO_4}$ → potassium tetraoxidochromate(VI), $\mathrm{KMnO_4}$ → potassium tetraoxidomanganate(VII).

⚠️ "Dipotassium" Is Wrong

Option (3) prefixes potassium with "di" — old style. Modern IUPAC drops cation multipliers because the formula already encodes them. Likewise, "permanganate" (option 1) is a common name, not an IUPAC name.

$\boxed{\text{Answer: (2) Potassium tetraoxidomanganate(VI)}}$