Question

Zinc granules were added to Zinc Sulphate, Copper Sulphate, Aluminium Sulphate and Iron Sulphate solutions as shown below. You would observe the deposition of metal on Zinc in beakers:

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

Answer 1

The correct option is B

II and IV

The explanation for the correct answer

Option B:

Part 1:

• In beaker I, no reaction will take place both the metals are the same ie. Zinc.

$$\begin{gathered} {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to \mathrm{No}\mathrm{reaction} \\ \mathrm{Zinc}\mathrm{Sulphate} \end{gathered}$$

Part 2:

• In beaker II, when a strip of Zinc is added to a solution of Copper Sulphate, Zinc will displace Copper from the Copper Sulphate (${\mathbf{CuSO}}_{\mathbf{4}}$) solution.
• The blue colour of the solution gradually becomes colourless due to the formation of Zinc Sulphate solution, and the red-brown Copper metal is deposited on the Zinc strip.

$$\begin{gathered} {\mathrm{CuSO}}_4\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ \mathrm{Copper}\mathrm{Zinc}\mathrm{Sulphate} \\ \mathrm{Sulphate} \end{gathered}$$

Part 3:

• In beaker III, Aluminium is more reactive than Zinc which implies the reaction won't be feasible.

$$\begin{gathered} {\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to \mathrm{No}\mathrm{reaction} \\ \mathrm{Aluminium} \\ \mathrm{Sulphate} \end{gathered}$$

Part 4:

• In beaker IV, When Zinc is added to a solution of Iron II Sulphate, Zinc will displace Iron from the Iron Sulphate (${\mathbf{FeSO}}_{\mathbf{4}}$) solution.
• The greenish colour of the solution gradually becomes colourless due to the formation of Zinc Sulphate solution, and Iron metal is deposited on the Zinc.

$$\begin{gathered} {\mathrm{FeSO}}_4\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to {\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)+\mathrm{Fe}\left(\mathrm{s}\right) \\ \mathrm{Iron}\mathrm{II}\mathrm{Zinc}\mathrm{Sulphate} \\ \mathrm{Sulphate} \end{gathered}$$

Hence, option (B) is correct. You would observe the deposition of metal on Zinc in beakers: II and IV.