Question

We can show that iron is more reactive than copper :
(1) by preparing copper sulphate solution and dipping iron strip in it
(2) by dipping both the strips in water for some time
(3) by preparing iron sulphate solution and dipping copper strip in it
(4) by heating both iron and copper strips

Answer 1

Iron is more reactive metal then copper, so iron displaces copper from blue coloured copper sulphate solution and forms light green coloured iron sulphate solution.
$\underset{\mathrm{Blue}}{{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Grey}}{\mathrm{Fe}\left(\mathrm{s}\right)}\to \underset{\mathrm{Green}}{{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Brown}}{\mathrm{Cu}\left(\mathrm{s}\right)}$
So, we prepare copper sulphate solution and dip an iron nail in it, it will give us easily observable results.

Hence, the correct answer is option 1.