D-And F-Block Elements Ques 182
Question: A blue colouration is not obtained when
[CBSE PMT 1989]
Options:
A) Ammonium hydroxide dissolves in copper sulphate
B) Copper sulphate solution reacts with $ K_4[Fe{{(CN)}_6}] $
C) Ferric chloride reacts with sodium ferrocyanide
D) Anhydrous $ CuSO_4 $ is dissolved in water
Show Answer
Answer:
Correct Answer: B
Solution:
$ CuSO_4+K_4[Fe{{(CN)}_6}]\to $ no reaction
$ 4NH_4OH+CuSO_4\to \underset{Deep,blue}{\mathop{[Cu{{(NH_3)}_4}]}}SO_4+4H_2O $
$ \underset{Anhydrous}{\mathop{CuSO_4}},+5H_2O\to \underset{Blue}{\mathop{CuSO_4}},.5H_2O $
$ 4FeCl_3+3Na_4[Fe{{(CN)}_6}]\to \underset{\begin{smallmatrix} Ferric,ferrocyanide \\ ,\text{(Prussian},\text{blue)} \end{smallmatrix}}{\mathop{Fe_4[Fe{{(CN)}_6}]}},+12NaCl $
