Question

Which of the following statement is correct? (a) Classical smog is reducing in nature. (b) Photochemical smog is oxidizing in nature. (c) Classical smog is formed in cool, humid climate while photochemical smog is formed in dry, warm climates. (d) All are correct.

Short answer

Statement (d) all are correct.

Step-by-step solution

Understand Classical Smog

Classical smog, also known as London smog, is typically caused by the combustion of fossil fuels, leading to the release of sulfur dioxide and particulate matter. It is known to be reducing in nature due to the presence of sulfur dioxide.

Understand Photochemical Smog

Photochemical smog, also known as Los Angeles smog, is formed when sunlight reacts with pollutants like hydrocarbons and nitrogen oxides. This type of smog has oxidizing properties due to the presence of ozone and other oxidants.

Climate Conditions for Both Types of Smog

Classical smog generally forms in cool, humid climates due to the interaction of moisture with sulfur dioxide. Photochemical smog forms in dry, warm climates where there is ample sunlight to drive the photochemical reactions.

Verify Each Statement

Statement (a) is correct because classical smog is reducing in nature. Statement (b) is correct because photochemical smog is oxidizing in nature. Statement (c) is correct because classical smog forms in cool, humid climates and photochemical smog forms in dry, warm climates. Hence, statement (d) is also correct since all the other statements are correct.

Key concepts

Classical Smog

Classical smog, also called London smog, occurs primarily due to the burning of fossil fuels like coal. When these fuels are burned, they release pollutants such as sulfur dioxide (SO₂) and particulate matter into the air. These pollutants combine with water vapor in the atmosphere to form a thick, heavy smog. Because this type of smog primarily involves the addition of sulfur dioxide, which is a reducing agent, classical smog is considered 'reducing' in nature.

Some key points about classical smog include:

• More common in cooler temperatures.
• Requires a humid environment to form effectively.
• Historically associated with industrial regions, most notably London.

It is particularly harmful to human health, causing respiratory issues and other ailments.

Photochemical Smog

Photochemical smog, often known as Los Angeles smog, is quite different from classical smog. This type forms when sunlight interacts with pollutants like hydrocarbons and nitrogen oxides (NOₓ). These reactions lead to the formation of other harmful compounds such as ozone (O₃), which are oxidizing in nature. This is why photochemical smog is also called 'oxidizing' smog.

Important aspects of photochemical smog include:

• Forms under high sunlight conditions.
• Common in places with a warm, dry climate.
• Major sources include vehicle emissions and industrial pollutants.

Photochemical smog can lead to eye irritation, reduced lung function, and other health issues. It is also bad for the environment, damaging crops and other vegetation.

Climate Conditions for Smog

Climate plays a significant role in the formation of both classical and photochemical smog.

For classical smog:

• Forms in cool and humid climates.
• Moisture in the air helps the pollutants combine and form a thicker smog.

This is why classical smog is often seen in places with frequent fog and cooler temperatures, like historical London.

For photochemical smog:

• Forms in warm and dry climates.
• Sunlight is a key driver for the chemical reactions that create this smog.

Typically, photochemical smog occurs in regions that receive a lot of sunlight and have less humidity, such as Los Angeles. The climate conditions greatly influence the type and severity of smog that can form in an area.