Science — CBSE Class 10 board question

Labelled Diagram — Electrolytic Refining of Copper:

```
Battery
+ –
| |
Anode Cathode
(Impure (Pure
Copper) Copper)
| |
___________________
| |
| CuSO₄ solution |
|___________________|
(Electrolyte)
```

(Diagram should show: battery connected to two copper electrodes dipped in copper sulphate (CuSO₄) solution, with anode labelled "impure copper" and cathode labelled "pure copper".)

What happens when electric current is passed:

When electric current is passed, the impure copper anode slowly dissolves into the CuSO₄ solution. Cu²⁺ ions from the solution get deposited as pure copper on the cathode. Insoluble impurities (like silver, gold) collect below the anode as anode mud.

• 1 mark for the correctly labelled diagram (anode = impure Cu, cathode = pure Cu, electrolyte = CuSO₄ solution, battery shown).
• 1 mark for stating anode dissolves / copper ions migrate to cathode.
• 1 mark for mentioning pure copper deposits at cathode AND impurities settle as anode mud.
• Examiners expect the term "anode mud" to be written explicitly — it fetches a mark.
• The diagram need not be elaborate; clear labels are what matter.