Which gas is identified by brown fumes in the decomposition of lead nitrate?
Answer and explanation
Correct answer: Nitrogen dioxide
On heating, lead nitrate decomposes according to 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂. Nitrogen dioxide, NO₂, is a reddish-brown gas, so its brown fumes provide a visible clue during the reaction. Oxygen is colourless, as are hydrogen and carbon dioxide under ordinary conditions. Therefore the gas identified by the brown fumes is nitrogen dioxide, making option B correct.
Frequently asked questions
What is the correct answer to this question?
Nitrogen dioxide
Why is this the correct answer?
On heating, lead nitrate decomposes according to 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂. Nitrogen dioxide, NO₂, is a reddish-brown gas, so its brown fumes provide a visible clue during the reaction. Oxygen is colourless, as are hydrogen and carbon dioxide under ordinary conditions. Therefore the gas identified by the brown fumes is nitrogen dioxide, making option B correct.
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.
