Question

Air pollutants that produce photochcmical oxidants includc (a) \(\mathrm{CO}_{2}, \mathrm{CO}\) and \(\mathrm{SO}_{2}\) (b) Oxygen, chlorine and nitric acid (c) Nitrous oxide, nitric oxide and nitric acid (d) Ozone, chlorine and sulphur dioxide

Short answer

Correct answer is (c).

Step-by-step solution

Understand the Question

Identify which compounds among the given options contribute to the formation of photochemical oxidants.

Recall Photochemical Oxidants Definition

Photochemical oxidants are secondary pollutants formed by the reaction of primary pollutants (like nitrogen oxides and volatile organic compounds) with sunlight.

Analyze Each Option

Option (a): \(\mathrm{CO}_{2}, \mathrm{CO}\) and \(\mathrm{SO}_{2}\) do not all contribute to photochemical oxidants. Option (b): Oxygen and chlorine are not significant contributors to photochemical oxidants. Option (c): Nitrous oxide, nitric oxide, and nitric acid are associated with the formation of photochemical oxidants. Option (d): Ozone is a photochemical oxidant, but chlorine and sulphur dioxide are not primary contributors.

Choose the Correct Option

Based on the analysis, the correct option is (c), as nitrous oxide, nitric oxide, and nitric acid contribute to the formation of photochemical oxidants.

Key concepts

secondary pollutants

Secondary pollutants are a vital topic in environmental science. They are not emitted directly into the air. Instead, they form when primary pollutants react with other components in the atmosphere. This can involve different chemicals or sunlight.

For instance, photochemical oxidants like ozone are secondary pollutants. They are created when primary pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight.

Understanding the dynamics between primary and secondary pollutants helps in addressing air quality issues.

Remember: Primary pollutants come directly from a source, secondary pollutants form in the atmosphere.

nitrogen oxides

Nitrogen oxides, often abbreviated as NOx, are critical to understanding air pollution. These compounds include nitrogen dioxide (NO2) and nitric oxide (NO).

Nitrogen oxides are primary pollutants that primarily come from burning fossil fuels. This can happen in cars, power plants, and other industrial processes.

Once in the atmosphere, NOx can react with other substances to form secondary pollutants like ozone. This process usually requires sunlight, making it more common during the day.

These reactions can lead to the formation of photochemical smog, which affects air quality and human health. Therefore, controlling NOx emissions can significantly improve environmental conditions.

volatile organic compounds

Volatile Organic Compounds, or VOCs, are another important player in the air pollution game. They are carbon-containing chemicals that readily evaporate at room temperature.

VOCs come from many sources:

• Paints
• Industrial processes
• Vehicle emissions
• Cleaning products

More importantly, VOCs react with nitrogen oxides under sunlight to produce photochemical smog. This includes the formation of secondary pollutants like ozone.

The interaction between VOCs and NOx is particularly critical in urban environments where both pollutants are often present. Managing VOC emissions can, thus, help reduce air pollution levels significantly.