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Science · 2025 · 2 marks
CBSE 2025 · Region 5 · Set 3 · Q26
A copper wire on burning in flame, gets coated with a black substance. Write the chemical equation of the reaction that takes place. How can this…
A copper wire on burning in flame, gets coated with a black substance. Write the chemical equation of the reaction that takes place. How can this chemical change be reversed ?
Marking-scheme solution
\[2 \mathrm{Cu}+\mathrm{O}_{2} \xrightarrow{\text { heat }} 2 \mathrm{CuO}
\]
Hydrogen gas is passed over heated CuO. /
\[\mathrm{CuO}+\mathrm{H}_{2} \xrightarrow{\text { heat }} \mathrm{Cu}+\mathrm{H}_{2} \mathrm{O}
\]
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CBSE Class 10 Science past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.