Question

The colour of light absorbed by an aqueous solution of $CuS{O}_4$ is

• A. Orange red
• B. Blue green
• C. Yellow
• D. Violet

Answer 1

The correct option is B Blue green

$H{g}^{2+}+2I^{⊝}\to Hg{I}_2\downarrow$ (Scarlet red precipitate)
$Hg{l}_2+2I^{⊝}\to [Hg{I}_4{]}^{2-}$
$H{g}^{2+}+Co(SCN{)}_2\to Hg(SCN{)}_2\downarrow +C{o}^{2+}$
(Deep-blue crystalline solid)