Match the complexes in List I with the number of unpaired electrons in List II. List I: (P) [Fe(CN)6]^4-, (Q) [Fe(H2O)6]^2+, (R) [FeF6]^3-, (S) [Fe(CN)6]^3-. List II: (1) 0, (2) 1, (3) 4, (4) 5.

JEE Advanced levelSingle correct optionDifficulty 3 of 3df152

Match the complexes in List I with the number of unpaired electrons in List II. List I: (P) $[Fe (CN) X_{6}] X^{4 -}$ , (Q) $[Fe (H X_{2} O) X_{6}] X^{2 +}$ , (R) $[FeF X_{6}] X^{3 -}$ , (S) $[Fe (CN) X_{6}] X^{3 -}$ . List II: (1) 0, (2) 1, (3) 4, (4) 5.

P: Fe(II)

d^{6}

low spin, 0. Q: Fe(II)

d^{6}

high spin, 4. R: Fe(III)

d^{5}

high spin, 5. S: Fe(III)

d^{5}

low spin, 1. This gives P-1, Q-3, R-4, S-2.