Methane (CH4)

A) Is a green-house gas

B) Is a polycyclic Aromatic Hydrocarbon

C) Is a component in determining Air quality Index (AQI)

D) Helps in formation of Ozone

E) Is a Organic Compound (VOC)

Choose the correct answer from the options given below:

The correct option is A, D & E only.

Let us analyze each statement step-by-step to understand why this option is correct:

Statement A: Methane is a greenhouse gas (Correct)
Methane
${\mathrm{CH}}_4$
is a potent greenhouse gas. It is highly efficient at trapping infrared radiation in the Earth's atmosphere, having a global warming potential that is significantly greater than that of carbon dioxide over a 100-year timescale.

Statement B: Methane is a polycyclic Aromatic Hydrocarbon (Incorrect)
Methane is the simplest aliphatic hydrocarbon (an alkane) consisting of a single carbon atom bonded to four hydrogen atoms. It is not an aromatic compound and does not contain any ring structures, meaning it is not a polycyclic aromatic hydrocarbon (PAH).

Statement C: Methane is a component in determining Air Quality Index (AQI) (Incorrect)
The Air Quality Index (AQI) is typically calculated using major criteria air pollutants that directly impact human health at ground level. These standard pollutants include particulate matter
${\mathrm{PM}}_{2.5}$
and
${\mathrm{PM}}_{10}$
, nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, and ammonia. Methane is not directly monitored as a criteria pollutant for standard AQI calculations.

Statement D: Methane helps in the formation of Ozone (Correct)
Methane is a precursor to tropospheric (ground-level) ozone. Through photochemical reactions in the atmosphere, methane reacts with hydroxyl radicals in the presence of sunlight and nitrogen oxides to generate ozone, which acts as a greenhouse gas and an air pollutant.

Statement E: Methane is a Volatile Organic Compound (VOC) (Correct)
Methane is a carbon-based compound that vaporizes easily into the atmosphere under normal conditions, which classifies it chemically as a Volatile Organic Compound (VOC). While environmental regulations sometimes distinguish between methane and other VOCs (referring to the latter as Non-Methane VOCs or NMVOCs), methane is fundamentally a VOC.

Based on the analysis, statements A, D, and E are correct.