Question

When lead nitrate is heated, the colour of $\mathrm{PbO}$ and ${\mathrm{NO}}_2$ observed is respectively

• A. yellow and colourless
• B. colourless and brown
• C. yellow and brown
• D. green and brown

Answer 1

The correct option is C

yellow and brown

Option C

yellow and brown

Explanation of correct option:

• Decomposition reaction: Reaction in which reactant is broken down into two or more products in the presence of heat, light or electricity.
• $\mathrm{A}\to \mathrm{B}+\mathrm{C}$.
• Reaction:

$2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }2\mathrm{PbO}\left(\mathrm{s}\right)+4{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

Lead(II) nitrate Lead(II) oxide Nitrogen dioxide Oxygen

• Here in the presence of heat decomposition is taking place so it is known as thermal decomposition.
• Lead nitrate is decomposed into yellow colour lead(II) oxide and evolution of reddish-brown colour gas takes place which nitrogen dioxide.

So option A, B and D are incorrect.

Thus, the correct answer is Option C yellow and brown .