Question

Smog is a mixture of smoke and fog. Smog is mainly caused by pollutants from automobiles and industries when they (a) hit a dense shower of snow flakes (b) heat with oxygen in the air (c) react photochemically in the presence of UV light (d) form a smoke smog

Short answer

Option (c) react photochemically in the presence of UV light.

Step-by-step solution

Understand the components of smog

Smog is a type of air pollution composed of smoke, dust, and fog. It usually forms in urban areas and is a result of emissions from vehicles and industrial activities.

Analyze the options

Examine each given option to determine which best describes the process leading to the formation of smog:(a) hit a dense shower of snow flakes(b) heat with oxygen in the air(c) react photochemically in the presence of UV light(d) form a smoke smog

Eliminate incorrect options

Option (a) 'hit a dense shower of snow flakes' is incorrect as snowflakes do not cause smog.Option (b) 'heat with oxygen in the air' describes a reaction but does not specifically relate to smog formation.Option (d) 'form a smoke smog' is vague and redundant.

Identify the correct answer

Option (c) 'react photochemically in the presence of UV light' correctly describes the process of smog formation, particularly photochemical smog which is caused by the reaction of sunlight with pollutants like nitrogen oxides (NOx) and volatile organic compounds (VOCs).

Key concepts

air pollution

Air pollution is a significant environmental issue that impacts our health and the planet. It occurs when harmful substances, such as gases, particles, and biological molecules, are released into the atmosphere. These pollutants can come from various sources, including:

• Vehicles, like cars, trucks, and buses
• Industrial processes, such as factories and power plants
• Agricultural activities, which produce dust and chemicals
• Natural sources, like volcanoes and wildfires

One of the most concerning types of air pollution is caused by urban emissions from densely populated areas. When these pollutants accumulate, they can lead to the formation of smog and other health hazards. Understanding the sources and impacts of air pollution is crucial in finding ways to reduce it and protect our environment.

photochemical smog

Photochemical smog is a specific type of air pollution that forms when sunlight reacts with pollutants in the air. It primarily includes nitrogen oxides (NOx) and volatile organic compounds (VOCs). This reaction produces harmful substances such as ozone, which can penetrate the lungs and trigger respiratory problems. Photochemical smog is most common in urban areas with heavy traffic and industrial activities. The main steps in its formation are:

• Emissions of NOx and VOCs into the air from vehicles and industries
• Exposure of these pollutants to sunlight, especially UV light
• A chemical reaction that transforms these pollutants into ozone and other harmful compounds

Photochemical smog is often visible as a brownish haze and can cause health issues like asthma, bronchitis, and other lung diseases. Reducing emissions through regulations and adopting cleaner technologies is essential to controlling photochemical smog.

urban emissions

Urban areas are hotspots for emissions due to the concentration of vehicles, industries, and human activities. These emissions contribute significantly to air pollution and smog formation. Key contributors to urban emissions include:

• Vehicles that release exhaust gases, such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons
• Industrial facilities that emit large quantities of pollutants during production processes
• Residential heating and cooking activities that generate smoke and particulate matter
• Construction activities that produce dust and debris

Urban emissions not only degrade air quality but also have direct and indirect effects on public health. Addressing these emissions involves:

• Implementing stricter emission standards for vehicles and industries
• Promoting the use of public transportation and cleaner energy sources
• Encouraging urban planning that reduces congestion and increases green spaces
• Increasing awareness and education about the impacts of air pollution

By tackling urban emissions, cities can improve air quality and create healthier living environments for their residents.