Ritika noted the initial colour of the solutions in beakers I, II, III and IV. After inserting zinc rods in each solution and leaving undisturbed for two hours, she noted the colour of each solution again. Mark the beakers in which colour change is observed ?

Options

A. I and II only
B. II and III
C. III and IV
D. I and IV

Answer

C

Explanation

In beaker I, no reaction takes place as Zn is less reactive than Al. in beaker II, Zn is dipped in solution of its own ions. In beaker III, colour of the solution changs as Zn is more reactive than Fe and displaces Fe from `FeSO_(4)` solution.
`Zn+underset(("green solution"))(FeSO_(4)) to underset(("Colourless solution"))(ZnSO_(4))+Fe`
Similarly, in beaker IV, Zn being more reactive than Cu, displaces Cu from `CuSO_(4)` solution.
`Zn+underset(("blue solution"))(CuSO_(4)) to underset(("Colourless solution"))(ZnSO_(4))+Cu`