Question

Select the correct answer from the choices A, B, C, and D which are given. Write only the letter corresponding to the correct answer.

Lead nitrate on heating gives lead oxide, nitrogen dioxide, and oxygen. This reaction is known as:

• A. Combustion
• B. Combination
• C. Displacement
• D. Decomposition

Answer 1

The correct option is D

Decomposition

Explanation for the correct option:

Option D

Decomposition reaction:

• When the molecules of one substance split into two or more simpler substances, the reaction is called a decomposition reaction.
• These reactions are brought about in the presence of an external agent such as heat, light, and electricity.

For example:

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

Therefore, option D is correct.

Explanation for the incorrect option:

Option A

Combustion:

• A combustion reaction is a chemical reaction in which a fuel or substance undergoes oxidation by reacting with an oxidizing agent, resulting in the release of energy usually in the form of heat.
• Combustion reactions are generally highly exothermic redox reactions between an oxidant and a fuel.

${\mathrm{CH}}_{4\left(\mathrm{g}\right)}+2{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

Therefore, option A is incorrect.

Option B

Synthesis or combination reaction:

• When the molecules of two or more substances combine to form molecules of a single substance, the reaction is called a combination reaction.
• Combination reaction is also called synthesis reaction.

For example:

${\mathrm{C}}_{\left(\mathrm{s}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to {\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

Therefore, option C is incorrect.

Option C

Simple displacement reaction:

• Displacement reaction is also called substitution reaction.
• These are the reactions involving the displacement of an element from a compound by another element that takes its place.
• The ability of an element to displace another is determined by its relative position in an electrochemical series.

For example:

${\mathrm{Zn}}_{\left(\mathrm{s}\right)}+{\mathrm{CuSO}}_{4\left(\mathrm{aq}\right)}\to {\mathrm{ZnSO}}_{4\left(\mathrm{aq}\right)}+{\mathrm{Cu}}_{\left(\mathrm{s}\right)}$

Therefore, option C is incorrect.

Therefore, option D is correct.