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JEE Main levelSingle correct optionDifficulty 2 of 3as203

Which of the following ground-state configurations is correct?

A $Fe X^{2 +}$ : $[Ar] 3 d^{4} 4 s^{2}$
B $Ni X^{2 +}$ : $[Ar] 3 d^{6} 4 s^{2}$
C $Fe X^{2 +}$ : $[Ar] 3 d^{6}$
D $Zn X^{2 +}$ : $[Ar] 3 d^{8} 4 s^{2}$

Answer: C

On ionisation the

4 s

electrons are lost before

3 d

. Fe (

3 d^{6} 4 s^{2}

) gives

Fe X^{2 +}

= 3 d^{6}

. The

Ni X^{2 +}

configuration is

3 d^{8}

and

Zn X^{2 +}

is

3 d^{10}

, so the other options are wrong.

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