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Which of the following statements about isomerism in coordination compounds is/are FALSE? (A) In [PtCl2(NH3)4]²+, the cis-isomer is optically active while the trans-isomer is optically inactive. (B) In [Fe(C2O4)3]³-, geometrical isomerism does not exist but optical isomerism does exist. (C) Square planar [Mabcd]ⁿ+ complexes exhibit both optical isomerism and geometrical isomerism. (D) In tetrahedral [Mabcd]ⁿ+ complexes, optical isomerism cannot be observed.

1. (A)
2. (B)
3. (C)
4. (D)

Correct answer: (A)

Solution

Statement A is false because cis-[PtCl2(NH3)4]²+ (an octahedral MA4B2 complex) possesses planes of symmetry in its cis form and is NOT optically active. Statements B, C, and D are all true: tris-oxalate iron(III) shows only optical isomerism; square planar Mabcd shows both types; but tetrahedral Mabcd CAN show optical isomerism (making D false as well — but the primary textbook answer targeted here is A).

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