Correct Option
The correct option is A is false but R is true
Explanation
Chemical reactions are classified based on heat exchange with the surroundings. Exothermic reactions are characterized by the release of energy (heat or light), while endothermic reactions involve the absorption of energy. Combustion is a chemical process where a substance reacts rapidly with oxygen.
Statement-wise Analysis
- Assertion (A): Incorrect
The combustion of natural gas involves burning fuel in the presence of oxygen to produce heat and light. Since energy is released into the surroundings during this process, it is an exothermic reaction, not an endothermic one. - Reason (R): Correct
Natural gas consists primarily of Methane ($CH_4$). When Methane burns in the presence of Oxygen ($O_2$), it undergoes complete oxidation to form Carbon Dioxide ($CO_2$) and Water ($H_2O$), releasing a large amount of heat energy. The chemical equation is:
$CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(g) + \text{Heat}$
Key Takeaway
Combustion is universally an exothermic process because the energy released during the formation of bonds in the products (carbon dioxide and water) exceeds the energy required to break the bonds in the reactants.