Four students A,B,C and D noted the initial colour of the solutions in beakers I, II, III and IV. After inserting zinc rods in each solution and leaving it undisturbed for two hours, noted the colour of each solution again.

They recorded their observations in thr form of a table given below:

Which student noted the colour change in all four beakers correctly?

Options

A. P
B. Q
C. R
D. S

Answer

D

Explanation

The reactivity of metals is in the order :
`AlgtZngtFegtCu`
Thus, in beaker I, no reaction takes place, colourless solution remains colourless.
In beaker II, no reaction takes place.
In beaker III, reaction takes place as follows:
`Zn+underset(("Light green"))(FeSO_(4))tounderset(("Colourless"))(ZnSO_(4))+Fe`
In beaker IV, reaction takes place as follows:
`Zn+underset(("Blue"))(CuSO_(4))tounderset(("Colourless"))(ZnSO_(4))+Cu`