Match List - I with List - II :

Choose the correct answer from the options given below :

To obtain the correct correspondence we recall the characteristic features of the four common electro-chemical devices given in List-I and then look for the statement in List-II that uniquely describes each one.

• It employs a zinc anode dipped in $$ZnSO_4$$ and a copper cathode dipped in $$CuSO_4$$, kept apart by a salt bridge.
• The overall reaction is $$Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu$$.
Hence, statement III - “overall reaction $$Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu$$” - matches Daniell cell.

• The secondary (rechargeable) battery used in automobiles has lead and lead-dioxide electrodes with $$H_2SO_4$$ as electrolyte.
• On discharge it forms $$PbSO_4$$ on both plates but can be regenerated by charging.
Thus, statement I - “rechargeable battery used in automobiles” - matches the lead storage battery.

• The familiar primary (non-rechargeable) Leclanché cell contains a paste of $$NH_4Cl + ZnCl_2$$ around a zinc container (anode) and a graphite rod (cathode) surrounded by $$MnO_2$$.
• It is acidic in nature and cannot be recharged.
Therefore, statement IV - “non-rechargeable cell having an acidic paste electrolyte” - matches the dry cell.

• In this device hydrogen is oxidised and oxygen is reduced on inert porous electrodes, the only product being water; it is used where continuous supply of the two gases is possible (e.g. spacecraft).
Consequently, statement II - “used in spacecraft, products are only water” - matches the hydrogen-oxygen fuel cell.

Collecting all correct matches:

$$(A) \rightarrow (III),\; (B) \rightarrow (I),\; (C) \rightarrow (IV),\; (D) \rightarrow (II)$$

This combination corresponds to Option C.