Question

Pick up the incorrect statements here. (1) Classical smog is good for health but not photo chemical smog. (2) During formation of smog the level of ozone in the atmosphere goes down. (3) Classical smog has an oxidizing character while the photochemical smog is reducing in character. (4) Photochemical smog occurs in day time whereas the classical smog occurs in early morning hours. (a) 1,2 and 3 (b) 1,3 and 4 (c) 2 and 3 only (d) 3 and 4 only

Short answer

The incorrect statements are (1), (2), and (3), so option (a) is correct.

Step-by-step solution

Evaluate Statement (1)

Statement (1) says, 'Classical smog is good for health but not photochemical smog.' Classical smog, also known as London smog, is formed from sulfur dioxide and is not good for health as it causes respiratory issues, similar to photochemical smog which contains pollutants like ozone. Hence, this statement is incorrect.

Evaluate Statement (2)

Statement (2) claims, 'During formation of smog the level of ozone in the atmosphere goes down.' In reality, photochemical smog results in an increase in ozone levels due to the reaction of sunlight with pollutants. Therefore, this statement is incorrect.

Evaluate Statement (3)

Statement (3) states, 'Classical smog has an oxidizing character while the photochemical smog is reducing in character.' Classical smog is reducing in nature due to the presence of sulfur compounds, whereas photochemical smog is oxidizing because of the presence of substances like ozone. This makes the statement incorrect.

Evaluate Statement (4)

Statement (4) says, 'Photochemical smog occurs in the daytime, whereas classical smog occurs in early morning hours.' This statement is correct as photochemical smog forms in the presence of sunlight, typically during the day, while classical smog tends to form in cooler times such as in the early morning.

Determine the Incorrect Statements

Based on the evaluations, the incorrect statements are (1), (2), and (3). Therefore, the correct option for the incorrect statements is option (a) 1, 2, and 3.

Key concepts

Classical Smog

Classical smog, often referred to as London smog, is a type of air pollution that became notably prevalent in London in the 20th century. It primarily forms from the combustion of coal and characterized by its thick, grayish appearance. This type of smog typically arises in conditions of high humidity and cooler temperatures, often early in the morning.

Key components of classical smog include:

• Sulfur Dioxide (SO₂): A significant contributor sourced from the burning of sulfur-containing fossil fuels.
• Soot: Microscopic carbon particles that give the smog its sooty look.
• Water Vapor: It helps in creating the dense fog characteristic of this smog.

Despite its historic association, classical smog is not good for health. It can cause respiratory problems and exacerbate conditions like asthma, emphasizing its reducing nature due to the presence of sulfur compounds.

Ozone Formation

Ozone in the atmosphere plays a complex role, particularly in the context of smog. There are two main types of ozone - stratospheric and tropospheric.

In the context of smog, we refer to tropospheric ozone, a key component of photochemical smog. It forms when sunlight reacts with nitrogen oxides (NO_x) and volatile organic compounds (VOCs) from vehicle exhaust, industrial emissions, and natural sources.

• When sunlight hits these pollutants, chemical reactions occur, forming ground-level ozone.
• This ozone, unlike the protective layer high above in the stratosphere, is harmful to human health, causing respiratory issues and other health problems.
• It is also detrimental to vegetation and wildlife.

Consequently, ozone is part of the oxidizing character of photochemical smog, contributing to air pollution's overall impact on health and the environment.

Oxidizing and Reducing Character

Smogs can be classified as having oxidizing or reducing characteristics based on their chemical composition and effects on health and the environment.

• Oxidizing Smog (Photochemical): Characterized by its formation during the day by chemical reactions involving sunlight. It contains oxidizing agents like ozone ( O₃) and nitrogen oxides, which have harmful effects on health and the environment.
• Reducing Smog (Classical): Contains sulfur dioxide and is formed primarily from coal burning. It has a reducing nature because sulfur compounds render a reducing environment.

Understanding these properties is essential for distinguishing between different types of smog, their formation times, and health impacts. Reducing smogs can lead to respiratory issues, while oxidizing smogs can cause even wider-ranging environmental and health damage due to aggressive chemical behavior.

Air Pollution

Air pollution is a global environmental issue that arises from both natural and human activities, and it severely impacts human health, wildlife, and the planet.

Major categories include particulate matter, gases like carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen oxides (NO_x), and ozone. These pollutants are often the byproducts of burning fossil fuels, industrial processes, and even natural phenomena like wildfires.

• Long-term exposure to air pollution can lead to respiratory diseases, heart conditions, and even affect mental health.
• Air pollution is also linked to climate change, as many pollutants are greenhouse gases.
• Efforts to reduce air pollution include policies focused on reducing emissions from vehicles, industries, and encouraging the use of renewable energy sources.

Understanding air pollution and its causes is crucial for mitigating its effects and protecting both environmental and public health.