The question asks to identify the atmospheric layer where beneficial ozone is found, contrasting it with ground-level (tropospheric) ozone, which is harmful. This requires knowledge of the Earth's atmospheric layers and the role of ozone in each.
C) Stratosphere — The stratosphere contains the ozone layer, which is crucial for absorbing harmful ultraviolet radiation from the sun, thus protecting life on Earth. This is the "beneficial ozone" referred to in the question.
The question asks to identify the full form of 'PAN', a secondary pollutant in photochemical smog known for causing eye irritation and plant damage. This requires knowledge of common air pollutants and their chemical names.
Correct Option: C) Peroxyacetyl nitrate
Peroxyacetyl nitrate (PAN) is a key secondary pollutant formed during photochemical smog. It is highly irritating to the eyes and harmful to vegetation, causing bronzing and glazing of leaves.
The question asks for the definition of PM2.5 particulate matter based on its diameter. This is a direct recall question related to environmental science and air pollution.
A) 2.5 micrometres — PM2.5 is specifically defined as particulate matter with an aerodynamic diameter of 2.5 micrometres or less. The '2.5' in PM2.5 directly refers to this size limit.
The question asks to identify a heavy metal that was historically used as an anti-knock agent in petrol and is a hazardous air pollutant, specifically affecting the nervous system in children. We need to evaluate each option based on these criteria.
C) Lead is the correct answer. Tetraethyl lead was extensively used as an anti-knock additive in petrol. Its combustion released lead into the atmosphere, which is a potent neurotoxin, especially harmful to the developing nervous systems of children, causing cognitive and behavioral impairments.
Acid rain is a significant environmental issue caused by the emission of certain pollutants into the atmosphere. These pollutants react with water, oxygen, and other chemicals to form acidic compounds that fall to the Earth as rain, snow, fog, or dust. The question asks to identify the primary acids formed in this process.
Correct Option: B) Sulphuric acid and nitric acid are the two primary acids formed when atmospheric pollutants like sulfur dioxide and nitrogen oxides combine with rainwater.
The question asks to identify the toxic gas responsible for the Bhopal gas tragedy. This requires knowledge of major historical industrial disasters and the specific chemicals involved.
Correct Option: B) Methyl isocyanate (MIC) was the highly toxic gas that leaked from the Union Carbide India Limited (UCIL) pesticide plant in Bhopal on the night of December 2-3, 1984, leading to the devastating Bhopal gas tragedy. Exposure to MIC causes severe respiratory problems, blindness, and other debilitating conditions, leading to thousands of deaths and long-term health issues for many more.