NCERT Class 10 Science — Chapter 1: Chemical Reactions & Equations

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What is the chemical identity of the solid residue obtained upon strongly heating lead nitrate?

Official previous-year question

Verified 1 Aug 2026.

Options

ALead sulphate
BLead carbonate
CLead(IV) oxide
DLead(II) oxide

Did you get this right?

Solution

The correct option is Lead(II) oxide.

Explanation

The question pertains to a thermal decomposition reaction. This is a category of chemical reactions where a single compound breaks down into two or more simpler substances when subjected to heat.

Analysis of the Reaction:
When lead nitrate is heated strongly, it undergoes decomposition. The reaction yields lead(II) oxide, nitrogen dioxide, and oxygen. The balanced chemical equation is:

2Pb(NO₃)₂ (s) $\xrightarrow{\text{Heat}}$ 2PbO (s) + 4NO₂ (g) + O₂ (g)

Lead(II) oxide (PbO): This forms the solid residue. It is yellow in colour (often appearing reddish-yellow when hot and yellow when cold).
Nitrogen dioxide (NO₂): This is observed as characteristic reddish-brown fumes emitted during the reaction.
Oxygen (O₂): A colourless gas is also released.

Therefore, the chemical identity of the solid residue is Lead(II) oxide.

Key Takeaway:
The thermal decomposition of lead nitrate produces a yellow solid residue of Lead(II) oxide and evolves brown fumes of Nitrogen dioxide.

Your note

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The correct option is Lead(II) oxide.

Explanation

The question pertains to a thermal decomposition reaction. This is a category of chemical reactions where a single compound breaks down into two or more simpler substances when subjected to heat.

Analysis of the Reaction:
When lead nitrate is heated strongly, it undergoes decomposition. The reaction yields lead(II) oxide, nitrogen dioxide, and oxygen. The balanced chemical equation is:

2Pb(NO₃)₂ (s) $\xrightarrow{\text{Heat}}$ 2PbO (s) + 4NO₂ (g) + O₂ (g)

Lead(II) oxide (PbO): This forms the solid residue. It is yellow in colour (often appearing reddish-yellow when hot and yellow when cold).
Nitrogen dioxide (NO₂): This is observed as characteristic reddish-brown fumes emitted during the reaction.
Oxygen (O₂): A colourless gas is also released.

Therefore, the chemical identity of the solid residue is Lead(II) oxide.

Key Takeaway:
The thermal decomposition of lead nitrate produces a yellow solid residue of Lead(II) oxide and evolves brown fumes of Nitrogen dioxide.