Question

Which of the following pollutants is naturally released from marshes and paddy fields and is also the most abundant hydrocarbon in the atmosphere?

• A. Benzene
• B. Methane
• C. Ethylene
• D. Nitrous oxide

Answer 1

Answer:

B. Methane

• Correct Answer: Option B - Methane

• Methane (CH₄) is the correct answer because it is naturally released from marshes and paddy fields and is indeed the most abundant hydrocarbon in Earth's atmosphere.

• Methane is produced in wetlands like marshes through a process called methanogenesis, where anaerobic bacteria decompose organic matter in oxygen-poor environments.

• In paddy fields (rice cultivation), the flooded conditions create an anaerobic environment where methanogenic bacteria thrive, producing significant amounts of methane.

• Methane is classified as a hydrocarbon because its chemical structure consists only of carbon and hydrogen atoms (CH₄).

• With an atmospheric concentration of about 1.8 parts per million, methane is far more abundant than any other hydrocarbon in the atmosphere.

• While other options like benzene and ethylene are also hydrocarbons, they exist in much lower concentrations in the atmosphere and are not significantly produced in marshes or paddy fields.

• Nitrous oxide is not a hydrocarbon at all (it contains nitrogen and oxygen, not carbon and hydrogen).