Which pair correctly identifies the brown gas and the colourless gas produced when lead nitrate is heated?
Answer and explanation
Correct answer: Nitrogen dioxide and oxygen
Lead nitrate undergoes thermal decomposition:
\[
2\mathrm{Pb(NO_3)_2} \xrightarrow{\Delta} 2\mathrm{PbO} + 4\mathrm{NO_2} + \mathrm{O_2}
\]
\(\mathrm{NO_2}\) is the brown gas, while \(\mathrm{O_2}\) is colourless. Option B incorrectly names nitrogen gas; nitrogen is released in this reaction as \(\mathrm{NO_2}\), not as \(\mathrm{N_2}\).
Frequently asked questions
What is the correct answer to this question?
Nitrogen dioxide and oxygen
Why is this the correct answer?
Lead nitrate undergoes thermal decomposition:
\[
2\mathrm{Pb(NO_3)_2} \xrightarrow{\Delta} 2\mathrm{PbO} + 4\mathrm{NO_2} + \mathrm{O_2}
\]
\(\mathrm{NO_2}\) is the brown gas, while \(\mathrm{O_2}\) is colourless. Option B incorrectly names nitrogen gas; nitrogen is released in this reaction as \(\mathrm{NO_2}\), not as \(\mathrm{N_2}\).
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
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