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Science · 2026 · 4 marks
CBSE 2026 · Region 1 · Set 1 · Q28
Read the following passage and answer the questions given below : Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like - Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals.(a)Why carbonate or sulphide ores are converted to oxides before extraction of metal from it ?(b)Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide.(c)How is copper obtained from its ore $\displaystyle \left(\mathrm{Cu}_{2} \mathrm{~S}\right)$ ? Give equations of the reactions.(ii)(I)Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent ?(II)Why solder, an alloy of lead and tin, is used for welding electrical wires together ?
Read the following passage and answer the questions given below : Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like - Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals.
(a)
Why carbonate or sulphide ores are converted to oxides before extraction of metal from it ?
(b)
Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide.
(c)
How is copper obtained from its ore $\displaystyle \left(\mathrm{Cu}_{2} \mathrm{~S}\right)$ ? Give equations of the reactions.
(ii)
(I)
Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent ?
(II)
Why solder, an alloy of lead and tin, is used for welding electrical wires together ?
Marking-scheme solution
(a)
Because it is easier to obtain metal from its oxide. / Because it is easier to reduce metal oxide to metal
(b)
\[\begin{aligned}
& \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s})+2 \mathrm{Al}(\mathrm{~s}) \rightarrow 2 \mathrm{Fe}(\mathrm{l})+\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+\text { Heat } \\
& 3 \mathrm{MnO}_{2}(\mathrm{~s})+4 \mathrm{Al}(\mathrm{~s}) \rightarrow 3 \mathrm{Mn}(\mathrm{l})+2 \mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+\text { Heat }
\end{aligned}
\] (balancing is optional)
(i)
\(\displaystyle 2 \mathrm{Cu}_{2} \mathrm{~S}+3 \mathrm{O}_{2}(\mathrm{~g}) \xrightarrow{\text { Heat }} 2 \mathrm{Cu}_{2} \mathrm{O}(\mathrm{s})+2 \mathrm{SO}_{2}(\mathrm{~g})\)
\[2 \mathrm{Cu}_{2} \mathrm{O}+\mathrm{Cu}_{2} \mathrm{~S} \xrightarrow{\text { Heat }} 6 \mathrm{Cu}(\mathrm{~s})+\mathrm{SO}_{2}(\mathrm{~g})
\] OR
(c) (ii) (I) Because highly reactive metals have more affinity for oxygen than carbon.
(II) Because of its low melting point.
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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.