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Question: Statement-I: $[Fe(CN)_6]^{3-}$ is more stable than $[Fe(CN)_6]^{4-}$ Statement-II: $[Co(NH_3)_6]^{3+...

Statement-I: [Fe(CN)6]3−[Fe(CN)_6]^{3-} is more stable than [Fe(CN)6]4−[Fe(CN)_6]^{4-} Statement-II: [Co(NH3)6]3+[Co(NH_3)_6]^{3+} is more stable than [Co(en)2(NH3)2]3+[Co(en)_2(NH_3)_2]^{3+} In the light of the above statements, choose the correct answer from the options given below.

A

Both Statement-I and Statement-II are true

B

Both Statement-I and Statement-II are false

C

Statement-I is true and Statement-II is false

D

Statement-I is false and Statement-II is true

Answer

Both Statement-I and Statement-II are false.

Explanation

Solution

Statement-I is false because the standard reduction potential for the couple [Fe(CN)6]3−/[Fe(CN)6]4−[Fe(CN)_6]^{3-} / [Fe(CN)_6]^{4-} is +0.36+0.36 V. A positive reduction potential indicates that [Fe(CN)6]4−[Fe(CN)_6]^{4-} is the more stable species. Statement-II is false due to the chelate effect. Complexes with polydentate ligands (like ethylenediamine) are more stable than those with monodentate ligands (like ammonia). Therefore, [Co(en)2(NH3)2]3+[Co(en)_2(NH_3)_2]^{3+} is more stable than [Co(NH3)6]3+[Co(NH_3)_6]^{3+}.