Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Statement I is true but Statement II is false
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is false but Statement II is true
Answer
(2) Both Statement I and Statement II are true
Solution
Statement I: H2O is a weak field ligand ( o < P), so both complexes are high spin.
Cr2+ (3d4): t2g3eg1 CFSE = 3(-0.4 o) + 1(0.6 o) = -0.6 o
Mn2+ (3d5): t2g3eg2 CFSE = 3(-0.4 o) + 2(0.6 o) = 0
CFSE (magnitude) of the Cr(II) complex is greater. Statement I is true.
Statement II: CN- is a strong field ligand (low spin).
K3[Fe(CN)6]: Fe3+ (3d5) t2g5, n = 1 = 1(1+2) = 1.73 BM
Na4[Fe(CN)6]: Fe2+ (3d6) t2g6, n = 0 = 0
Statement II is true.
Answer: (2)