Question

A student was asked to carry out a chemical reaction by placing four different metal strips in CuSO₄ solution for a considerable time, one by one. Which of the following metal strip will turn the blue CuSO₄ solution to a light green solution in due course of time ?
(1) Fe
(2) Au
(3) Mg
(4) Ag

Answer 1

Copper sulphate solution is a blue colour solution, which on reaction with iron gives a green coloured solution of iron sulphate.

$\underset{\mathrm{Blue}}{{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Grey}}{\mathrm{Fe}\left(\mathrm{s}\right)}\to \underset{\mathrm{Green}}{{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Brown}}{\mathrm{Cu}\left(\mathrm{s}\right)}$

Hence, the correct answer is option 1.