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Science · 2026 · 3 marks
CBSE 2026 · Region 4 · Set 1 · Q27
Attempt either option (A) or (B).(i)Which method will be used to convert each of them to their respective metal oxides?(a)Carbonate ore(b)Sulphide ore(ii)Write a chemical reaction to illustrate the use of aluminium for joining cracked railway tracks.(iii)During extraction of metals, electrolytic refining is used to obtain pure metals. Which material will be used as anode and cathode for the refining of copper metal by this process ?(i)Write all the reactions involved in the extraction of Zn from ZnS.(ii)Hydrogen gas is not evolved when most of the metals react with nitric acid. Give reason.
Attempt either option (A) or (B).
(i)
Which method will be used to convert each of them to their respective metal oxides?
(a)
Carbonate ore
(b)
Sulphide ore
(ii)
Write a chemical reaction to illustrate the use of aluminium for joining cracked railway tracks.
(iii)
During extraction of metals, electrolytic refining is used to obtain pure metals. Which material will be used as anode and cathode for the refining of copper metal by this process ?
(i)
Write all the reactions involved in the extraction of Zn from ZnS.
(ii)
Hydrogen gas is not evolved when most of the metals react with nitric acid. Give reason.
Marking-scheme solution
(i) (a) Carbonate ore: Calcination
\[/ \mathrm{ZnCO}_{3}[\mathrm{~s}) \xrightarrow{\text { Heal }} \mathrm{ZnO}(\mathrm{~s})+\mathrm{CO}_{2}(\mathrm{~g})
\]
(b) Sulphide ore : Roasting
\[2 \mathrm{ZnS}(\mathrm{~s})+3 \mathrm{O}_{2}(\mathrm{~g}) \xrightarrow{\text { Heat }} 2 \mathrm{ZnO}(\mathrm{~s})+2 \mathrm{SO}_{2}(\mathrm{~g})
\]
(ii) \[\mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s})+2 \mathrm{Al}(\mathrm{~s}) \rightarrow 2 \mathrm{Fe}(\mathrm{l})+\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+\mathrm{Heat}
\]
(iii)
Anode: Impure copper rod.
Cathode: Pure copper strip.
OR
(i)
\[\begin{aligned}
& 2 \mathrm{ZnS}(\mathrm{~s})+3 \mathrm{O}_{2}(\mathrm{~g}) \xrightarrow{\text { Heat }} 2 \mathrm{ZnO}(\mathrm{~s})+2 \mathrm{SO}_{2}(\mathrm{~g}) \\
& \mathrm{ZnO}[\mathrm{~s})+\mathrm{C}(\mathrm{~s}) \rightarrow \mathrm{Zm}(\mathrm{~s})+\mathrm{CO}(\mathrm{~g})
\end{aligned}
\]
(ii)
Nitric acid is a strong oxidising agent and oxidises \(\displaystyle \mathrm{H}_{2}\) gas produced to water.
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CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.