29the answer is B..I read it in JD LEE that the compound given in B is soluble...
1)excess KCN is added to cupric salt and H2S is passed through the solution. no black CuS is precipitated because Cu is present in the solution as
a)[Cu(CN)6]4-
B)[Cu(CN)4]3-
C)[Cu(CN)4]2-
D)NONE.
2)Co3+ forms a complex with F- ion. the complex had a magnetic moment of 4.8BM. the hybridisation and geometry of the complex would be?
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4 Answers
29
21but govind i t have read it somewhere in ncert that Cu is more stable in +2 oxidation state than in +1 oxidation state........so shouldnt the answer be C?
29@saket wat u have read is right... Cu2+ is more stable than Cu+..and that's becsuse of the greater hydration energy released in case of Cu2+ ..but here in this case we have [Cu(CN)4]2- and [Cu(CN)4]3- ...more hydration energy will be released in case of [Cu(CN)4]3-..that may be the reason but i am not sure abt it...
Another example Au exists in +1 and +3 oxidation states..and +3 oxidation state is more stable..but wen Au forms complex with CN- (U may have read abt the complex in metallurgy chapter in the NCERT under the topic leaching and extraction of gold and silver) ..it exists in +1 oxidation state..
PS: Sometimes in inorganic it happens when u think logically u may get the wrong answer..but u shudnt feel disheartened...u shud learn frrom the mistake....coz inorganic chemistry is all abt learning and practicing more and more questions...