Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state?

Solution :
$$\eqalign{ & A{g_2}S{O_4} \to A{g^ + }\left( {4{d^{10}}} \right) - {\text{colourless}} \cr & Cu{F_2} \to C{u^{2 + }}\left( {3{d^9}} \right) - {\text{coloured}} \cr & Zn{F_2} \to Z{n^{2 + }}\left( {3{d^{10}}} \right) - {\text{colourless}} \cr & C{u_2}C{l_2} \to C{u^ + }\left( {3{d^{10}}} \right) - {\text{colourless}} \cr} $$