Free Atmospheric Pollution MCQs with Answers

21. Green house effect is NOT produced by the abundance of the gas called

• A. Methane
• B. CO2
• C. Nitrous oxide
• D. Sulphur dioxide

Explanation: The greenhouse effect is how heat is trapped close to Earth's surface by "greenhouse gases." Greenhouse gases include CO2, methane, and nitrous oxide which are options A, B, and C respectively. Option D, SO2, is an atmospheric pollutant produced by volcanic eruptions and combustion engines. It is mainly responsible for acid rain, not the greenhouse effect, making it the correct answer.

22. SO2 is responsible fir the formation of:

• A. Acid rain
• B. Green house effect
• C. Global warming
• D. Ozone depletion

Explanation: Acid rain: SO2 is a major contributor to the formation of acid rain. When released into the atmosphere, it reacts with water and other substances to form sulfuric acid, which can then fall to the Earth's surface as acid rain. Therefore, the correct option is "Acid rain" as SO2 is responsible for the formation of acid rain.

23. Chlorofluorocarbons are mainly responsible for:

• A. Air pollution
• B. Water pollution
• C. Acid rain
• D. Ozone layer depletion

Explanation: Chlorofluorocarbons (CFCs) are mainly responsible for ozone layer depletion.

24. C.F.C gases are produced from

• A. burning of coal
• B. burning of charcoal
• C. automobile engines
• D. refrigeration and air conditioning

Explanation: Chloroflorocarbons are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They react with the ozone and destroy it, making the layer thinner and allowing ultraviolet (UV) radiation to pass through it and fall on the earth's surface. This UV radiation can cause skin cancer and other ailments in humans and also affect plants and animals. The main source of CFC production is Coal combustion i.e. burning of coal. Among the given options, option A is correct because, unlike the rest, CFCs are released into the atmosphere, not produced.

25. Vehicular emissions, that are the major environmental concern, is

• A. CO2
• B. CO
• C. Low hydrocarbons
• D. All of them

Explanation: CO2 is the major vehicular emission responsible for causing the greenhouse effect and environmental pollution.

26. Tetraethyl lead (C2H2)4Pb is used as an antoknock agent and abandoned because of its hazardous product during the combustion of fuel. The hazardous product is

• A. CO2
• B. CO
• C. Lead
• D. Free radica ethyne (C2H2)

Explanation: TEL can cause chronic lead poisoning, and hence its hazardous product is lead.

27. Paper is a biodegradable material. It produces gas whose emission is environmentally objectionable. Which is that gas?

• A. CO2
• B. SO2
• C. CH4
• D. NO2

Explanation: When paper biodegrades, especially in the presence of oxygen, the primary gas emitted is carbon dioxide (CO2), due to the aerobic decomposition of its cellulose content. This process involves microorganisms breaking down the organic matter, releasing CO2 as a byproduct. Other gases like sulfur dioxide (SO2), methane (CH4), and nitrogen dioxide (NO2) are not typically emitted during the biodegradation of paper. SO2 is linked to burning sulfur-containing materials, CH4 is released in anaerobic conditions like landfills, and NO2 results from high-temperature combustion processes of fossil fuels.

28. Which one is not responsible for the formation of acid rain?

• A. CO2
• B. SO2
• C. CO
• D. NO2

Explanation: Acid rain is primarily caused by the dissolution of specific oxides in atmospheric moisture, leading to acidic compounds. Carbon monoxide (CO) is not capable of forming an acid when it reacts with water, thus it does not contribute to acid rain. In contrast, carbon dioxide (CO2) can form carbonic acid, sulphur dioxide (SO2) forms sulphuric acid, and nitrogen dioxide (NO2) forms nitric acid, all of which contribute to acid rain. Therefore, CO is the only option that does not lead to acid rain formation.

29. Which has the lowest temperature?

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Explanation: The top of the mesosphere, called the mesopause is the coldest part of the earth's atmosphere averaging about minus 130 degrees F. Hence the correct answer will be C.

30. Rain water becomes acidic, when the pH-value of rain water becomes _

• A. Greater than 6
• B. Greater than 6.5
• C. Less than 5.6
• D. Less than 5

Explanation: Normal clean rain has a pH value between 5.0 - 5.5, which is slightly acidic, however when rain combines with nitrogen oxides or SO2, it becomes more acidic has the pH drops below 5.0. Therefore the answer is D.