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Science · 2026 · 3 marks
CBSE 2026 · Region 5 · Set 3 · Q26
What happens when (i) potassium iodide solution is added to lead (II) nitrate solution? (ii) zinc is added to copper (II) chloride solution? (iii)…
What happens when
(i)
potassium iodide solution is added to lead (II) nitrate solution ?
(ii)
zinc is added to copper (II) chloride solution ?
(iii)
hydrogen gas is passed over hot copper (II) oxide ? Write balanced chemical equations of the reactions involved in support of your answer.
Marking-scheme solution
(i) Yellow precipitate of potassium iodide is formed.
\[2 \mathrm{KI}+\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} \rightarrow \mathrm{PbI}_{2}+2 \mathrm{KNO}_{3}
\]
(ii) Zinc will displace copper from copper chloride.
\[\mathrm{Zn}+\mathrm{CuCl}_{2} \rightarrow \mathrm{ZnCl}_{2}+\mathrm{Cu}
\]
(iii) The black coating of copper oxide will turn brown.
\[\mathrm{CuO}+\mathrm{H}_{2} \rightarrow \mathrm{Cu}+\mathrm{H}_{2} \mathrm{O}
\]
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