MCQEasyJEE 2024Ligands & Coordination Number

JEE Chemistry 2024 Question with Solution

The correct IUPAC name of K2MnO4\mathrm{K_2MnO_4} is:

  • A

    Potassium tetraoxopermanganate (VI)

  • B

    Potassium tetraoxidomanganate (VI)

  • C

    Dipotassium tetraoxidomanganate (VII)

  • D

    Potassium tetraoxidomanganese (VI)

Answer

Correct answer:B

Step-by-step solution

Standard Method

Given: The compound is K2MnO4\mathrm{K_2MnO_4}.

Find: The correct IUPAC name of the compound.

First determine the oxidation state of manganese. Potassium has oxidation state +1+1 and oxygen has oxidation state 2-2.

Using charge balance for the neutral compound:

2(+1)+x+4(2)=02(+1) + x + 4(-2) = 0

This simplifies to:

2+x8=02 + x - 8 = 0

So,

x=+6x = +6

Naming Logic

The anion MnO42\mathrm{MnO_4^{2-}} is named tetraoxidomanganate(VI) because it contains four oxygens and manganese is in the +6+6 oxidation state.

Adding the cation name gives Potassium tetraoxidomanganate (VI).

Therefore, the correct option is B.

Common mistakes

  • A common mistake is assigning manganese oxidation state +7+7 by confusing MnO42\mathrm{MnO_4^{2-}} with permanganate MnO4\mathrm{MnO_4^-}. Here the ion has charge 2-2, so manganese is +6+6, not +7+7.

  • Another mistake is using the older or incorrect name permanganate for this compound. According to IUPAC naming, the correct anion name is tetraoxidomanganate(VI).

  • Some students include the prefix di for potassium and write dipotassium unnecessarily. For this ionic compound, the cation is written as potassium, followed by the anion name.

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