ABenzene
BMethane
CEthylene
DNitrous oxide
Answer:
B. Methane
Read Explanation:
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).