Which of the following ions has the same number of unpaired electrons as Gd^3+ (4f^7)? (Atomic numbers: Np 93, Pu 94, Am 95, Cm 96.)

JEE Main levelSingle correct optionDifficulty 2 of 3df194

Which of the following ions has the same number of unpaired electrons as $Gd X^{3 +}$ ( $4 f^{7}$ )? (Atomic numbers: Np 93, Pu 94, Am 95, Cm 96.)

Cm is

5 f^{7} 6 d^{1} 7 s^{2}

, so

Cm X^{3 +}

5 f^{7}

with 7 unpaired electrons, like

Gd X^{3 +}

Am X^{3 +}

5 f^{6}

(6),

Pu X^{3 +}

5 f^{5}

(5) and

Np X^{3 +}

5 f^{4}

(4).