Match each complex in Column I with its spin-only magnetic moment in Column II (high spin for water, low spin for cyanide; [Cu(NH3)4]^2+ has one unpaired electron). Column I: P [Fe(H2O)6]^2+; Q [Fe(CN)6]^4-; R [Cr(H2O)6]^3+; S [Cu(NH3)4]^2+. Column II: 1) 0 BM; 2) 1.73 BM; 3) 3.87 BM; 4) 4.90 BM.

JEE Advanced levelSingle correct optionDifficulty 3 of 3cc048

Match each complex in Column I with its spin-only magnetic moment in Column II (high spin for water, low spin for cyanide; $[Cu (NH X_{3}) X_{4}] X^{2 +}$ has one unpaired electron). Column I: P $[Fe (H X_{2} O) X_{6}] X^{2 +}$ ; Q $[Fe (CN) X_{6}] X^{4 -}$ ; R $[Cr (H X_{2} O) X_{6}] X^{3 +}$ ; S $[Cu (NH X_{3}) X_{4}] X^{2 +}$ . Column II: 1) 0 BM; 2) 1.73 BM; 3) 3.87 BM; 4) 4.90 BM.

Fe(II) high spin

d^{6}

has 4 unpaired electrons (

24 = 4.90

). Fe(II) low spin

d^{6}

has 0. Cr(III)

d^{3}

has 3 (

15 = 3.87

). Cu(II)

d^{9}

has 1 (

3 = 1.73

). So P-4, Q-1, R-3, S-2.