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Science · 2026 · 3 marks
CBSE 2026 · Region 2 · Set 1 · Q27
Seema took a small amount of copper powder in a china dish and heated it. What changes will she observe on heating ? When $\displaystyle \mathrm{H}_{2}$ gas is passed over this heated substance, what visible changes will be seen in it ? Give the chemical equations of the reactions involved, along with the names and colours of the products in each case.
Seema took a small amount of copper powder in a china dish and heated it. What changes will she observe on heating ? When $\displaystyle \mathrm{H}_{2}$ gas is passed over this heated substance, what visible changes will be seen in it ? Give the chemical equations of the reactions involved, along with the names and colours of the products in each case.Marking-scheme solution
Colour of copper powder changes from brown to black.
On passing \(\displaystyle \mathrm{H}_{2}\) gas, the colour turns brown.
\[2 \mathrm{Cu}+\mathrm{O}_{2} \xrightarrow{\text { heat }} \underset{\substack{\text { copper oxide } \\ \text { (Black) }}}{2 \mathrm{CuO}}
\]
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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.