Which follows EAN Rule?

Na₄[Fe(CN)₆]

The correct answer is option 3. Na₄[Fe(CN)₆]

We know,

Effective Atomic number (EAN) = Atomic number of the central metal atom − Oxidation number of central metal − Coordination number

(1) \([Pd(NH_)3)_6]Cl_4\)

The atomic number of Palladium (Pd) is 46

Here, Pd is in + 4 oxidation state

\(∴ EAN = 46 − 4 + 12 = 54\)

(2) [Cr(NH₃)₅Cl] SO₄

The atomic number of Chromium (Cr) is 24

Here, Pd is in + 3 oxidation state

\(∴ EAN = 24 − 3 + 10 + 2 = 33\)

(3) Na₄[Fe(CN)₆]

The atomic number of Iron (Fe) is 26

Here, Pd is in + 2 oxidation state

\(∴ EAN = 26 − 2 + 12 = 36\)

Which resembles the electronic configuration of \(Kr\) which is 36. So, it follows EAN

(4) K₃[Fe(CN)₆]

The atomic number of Iron (Fe) is 26

Here, Pd is in + 3 oxidation state

\(∴ EAN = 26 − 3 + 12 = 35\)

So, the correct answer is (3) Na₄[Fe(CN)₆]