The appearance of brown gas on heating lead nitrate identifies which gas?
Answer and explanation
Correct answer: Nitrogen dioxide
On heating, lead nitrate undergoes thermal decomposition: 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂. Nitrogen dioxide, NO₂, is a reddish-brown gas, so its brown fumes provide the identifying observation. Oxygen is colourless, hydrogen is colourless and combustible, and carbon dioxide is colourless and does not produce brown fumes. Thus option B is correct.
Frequently asked questions
What is the correct answer to this question?
Nitrogen dioxide
Why is this the correct answer?
On heating, lead nitrate undergoes thermal decomposition: 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂. Nitrogen dioxide, NO₂, is a reddish-brown gas, so its brown fumes provide the identifying observation. Oxygen is colourless, hydrogen is colourless and combustible, and carbon dioxide is colourless and does not produce brown fumes. Thus option B is 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.
