Question

When lead nitrate is heated, it breaks down into lead monoxide, nitrogen dioxide, and oxygen

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

The reaction is an example of:

• A. Combination reaction
• B. Displacement reaction
• C. Decomposition reaction
• D. Double displacement reaction

Answer 1

The correct option is C

Decomposition reaction

Explanation for correct answer

(c ) decomposition reaction

• A decomposition reaction is a chemical reaction that occurs when one reactant disintegrates into two or more products.
• $2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\to 2\mathrm{PbO}\left(\mathrm{s}\right)+4{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$
• Here $\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2$, a single reactant breaks down into $2\mathrm{PbO},4{\mathrm{NO}}_2\mathrm{and}{\mathrm{O}}_2$
• So it is a decomposition reaction.

Explanation for incorrect answers:

(a) Combination reaction

• A combination reaction occurs when two reactants unite to generate one product.
• Here no two reactants unite to generate one product.
• So it is not a combination reaction

(b) Displacement reaction

• A displacement reaction occurs when an atom or a group of atoms in a molecule is replaced by another atom.
• In single displacement, either cation displaces cation or anion displaces anion, but both cannot occur together.
• So it is not a displacement reaction

.(d) Double displacement reaction

• A double displacement reaction occurs when two compounds react and the positive ions (cation) and negative ions (anion) of the two reactants transfer positions, resulting in the formation of two new compounds or products.
• Here no such reaction happens
• So it is not a double displacement reaction.

Therefore the correct option is ( C) Decomposition reaction. The reaction is an example of a decomposition reaction.