Which one of the following is the primary gaseous product formed during the complete combustion of coal in air?

The correct option is

Carbon dioxide

Explanation

Combustion is a chemical reaction between a fuel and an oxidant (usually atmospheric oxygen) that produces heat and gaseous products. The nature of the gaseous products depends heavily on the chemical composition of the fuel and the availability of oxygen during the process.

Detailed Analysis

• Complete Combustion: Coal is primarily composed of carbon. When it burns in the presence of a sufficient supply of air (oxygen), the carbon undergoes complete oxidation. The primary chemical reaction is the combination of carbon with oxygen to form Carbon dioxide (CO₂). This is the most abundant gaseous product formed.
• Incomplete Combustion: Carbon monoxide (CO) is produced primarily during incomplete combustion, which occurs when there is an insufficient supply of oxygen.
• Secondary Byproducts: Sulphur dioxide (SO₂) and Nitrogen dioxide (NO₂) are also produced during coal combustion. However, SO₂ arises from sulfur impurities within the coal, and NO₂ forms from the reaction of nitrogen (in the coal or air) at high temperatures. These are considered pollutants or secondary products, not the primary product of the carbon combustion itself.

Key Takeaway

The complete combustion of carbon-based fuels like coal, in the presence of adequate oxygen, primarily yields Carbon dioxide (CO₂). Incomplete combustion yields Carbon monoxide (CO).