Match the ions in Column I with their 4f configurations in Column II. Column I: P = Ce^3+, Q = Eu^3+, R = Gd^3+, S = Yb^3+. Column II: 1 = 4f^1, 2 = 4f^6, 3 = 4f^7, 4 = 4f^13.

JEE Main levelSingle correct optionDifficulty 2 of 3df180

Match the ions in Column I with their $4 f$ configurations in Column II. Column I: P = $Ce X^{3 +}$ , Q = $Eu X^{3 +}$ , R = $Gd X^{3 +}$ , S = $Yb X^{3 +}$ . Column II: 1 = $4 f^{1}$ , 2 = $4 f^{6}$ , 3 = $4 f^{7}$ , 4 = $4 f^{13}$ .

Ce (Z = 58) is

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

, so

Ce X^{3 +}

4 f^{1}

. Eu (63) is

4 f^{7} 6 s^{2}

, so

Eu X^{3 +}

4 f^{6}

. Gd (64) is

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

, so

Gd X^{3 +}

4 f^{7}

. Yb (70) is

4 f^{14} 6 s^{2}

, so

Yb X^{3 +}

4 f^{13}

. The mapping is P-1, Q-2, R-3, S-4.