Which pair correctly identifies the brown gas and the colourless gas formed 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 a brown gas, whereas \(\mathrm{O_2}\) is colourless. \(\mathrm{PbO}\) is a solid rather than a gas, so the correct pair is nitrogen dioxide and oxygen.
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 a brown gas, whereas \(\mathrm{O_2}\) is colourless. \(\mathrm{PbO}\) is a solid rather than a gas, so the correct pair is nitrogen dioxide and oxygen.
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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