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Science · 2024 · 3 marks
CBSE 2024 · Region 1 · Set 3 · Q33
(i)Define a decomposition reaction. Write chemical equation for the reaction that occurs when lead nitrate is heated strongly in a boiling tube.(ii)In electrolytic decomposition of water two gases are liberated at the electrodes. Give the mass ratio of the gas liberated at the cathode and at the anode.
(i)
Define a decomposition reaction. Write chemical equation for the reaction that occurs when lead nitrate is heated strongly in a boiling tube.
(ii)
In electrolytic decomposition of water two gases are liberated at the electrodes. Give the mass ratio of the gas liberated at the cathode and at the anode.
Marking-scheme solution
(i)
A reaction in which a single substance on absorption of energy. decomposes to give two or more substances.
\[2 \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2} \xrightarrow{\text { Heat }} 2 \mathrm{PbO}+4 \mathrm{NO}_{2}+\mathrm{O}_{2}
\]
(ii)
Cathode : Anode (Mass ratio) $\displaystyle 1$ : $\displaystyle 8$
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CBSE Class 10 Science past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.