Question

The colour of solution after half an hour when iron nails are dipped in copper sulphate solution is
a) pale green
b) blue
c) colourless
d) reddish brown

Answer 1

$$\begin{gathered} \mathrm{Dear}\mathrm{user}, \\ \mathrm{It}\mathrm{is}\mathrm{c})\mathrm{pale}\mathrm{green} \\ \mathrm{and}\mathrm{the}\mathrm{reaction}\mathrm{involved}\mathrm{is}: \\ {\mathrm{CuSO}}_4+{\mathrm{Fe}}^{2+}\to {\mathrm{FeSO}}_4+{\mathrm{Cu}}^{2+} \\ \mathrm{And}\mathrm{the}\mathrm{reason}\mathrm{behind}\mathrm{is},\mathrm{reactivity}\mathrm{series}\mathrm{that}\mathrm{is}\mathrm{iron}\mathrm{comes}\mathrm{before} \\ \mathrm{copper}\mathrm{in}\mathrm{the}\mathrm{reactivity}\mathrm{series}\mathrm{that}\mathrm{is}\mathrm{why}\mathrm{it}\mathrm{can}\mathrm{displace}\mathrm{copper}\mathrm{from} \\ \mathrm{its}\mathrm{solution}\mathrm{and}\mathrm{hence}\mathrm{the}\mathrm{colour}\mathrm{changes}\mathrm{to}\mathrm{pale}\mathrm{green}. \end{gathered}$$