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Science · 2024 · 4 marks
CBSE 2024 · Region 1 · Set 1 · Q37
The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.(i)What is the cathode and anode made of in the refining of copper by this process ?(ii)Name the solution used in the above process and write its formula.(iii)How copper gets refined when electric current is passed in the electrolytic cell ?You have two beakers 'A' and 'B' containing copper sulphate solution. What would you observe after about $\displaystyle 2$ hours if you dip a strip of zinc in beaker 'A' and a strip of silver in beaker 'B'? Give reason for your observations in each case.
The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.
(i)
What is the cathode and anode made of in the refining of copper by this process ?
(ii)
Name the solution used in the above process and write its formula.
(iii)
How copper gets refined when electric current is passed in the electrolytic cell ?
You have two beakers 'A' and 'B' containing copper sulphate solution. What would you observe after about $\displaystyle 2$ hours if you dip a strip of zinc in beaker 'A' and a strip of silver in beaker 'B'? Give reason for your observations in each case.
Marking-scheme solution
(i)
Cathode - Pure copper
Anode - Impure copper
(iii) (A)
Pure copper from the anode dissolves into electrolyte and an equivalent amount of pure metal from the electrolyte is deposited on cathode /
\[\text { At anode : } \mathrm{Cu} \longrightarrow \mathrm{Cu}^{++}+2 \mathrm{e}^{-}
\]
\[\text { At cathode : } \mathrm{Cu}^{++}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}
\]
The soluble impurities go into the solution whereas insoluble impurities settle down at the bottom of the anode.
[
OR
(iii) (B)In Beaker A : • The blue colour of the solution fades (or becomes colourless)
Reason - Zn is more reactive than copper
In Beaker B: • No change in colour.
Reason - Silver is less reactive than Copper
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.