Question

Which of the following does not form part of particulate matter?

• A. Fly ask
• B. Dust
• C. Aerosols
• D. Nitric oxide

Answer 1

Answer: (D)

Particulate matter consists of fine solids or liquid droplets that remain suspended in air. They are air pollutants and vary in chemical composition.

• Very tiny particulates having diameter 10 μm or less are known as PM10.
• Largely sized particulates can be grit (diameter of 500μm), fly ash and dust (diameter ranging between 0.25 - 500μm).
• Small sized particulates are fumes (less than 1μm), mist (liquid droplets of diameter less than 2μm) and aerosols (diameter of less than 1μm).

Hence, nitric oxide does not form a part of the particulate matter. Instead, it is responsible for acidic rain.

So, the correct answer is 'Nitric oxide'