Question

Consider the following features of a particular gas-

1. It is a reddish-brown gas with pungent smell.

2. It indirectly causes acid-rain.

Which of the following gases is being talked about?

1. CFC
2. SO₂
3. NO2
4. SO3

Answer 1

Correct Answer - Option 3 : NO2

Nitrogen Dioxide (NO₂) is one of a group of highly reactive gases known as oxides of nitrogen or nitrogen oxides.

• NO₂ is an intermediate in the industrial synthesis of nitric acid,
• At higher temperatures it is a reddish-brown gas with pungent smell.

• Interaction of NO₂ and other NO_x with water, oxygen and other chemicals in the atmosphere can form acid rain which harms sensitive ecosystems such as lakes and forests. 
• Elevated levels of NO₂ can also harm vegetation, decreasing growth, and reduce crop yields.

Hence we can conclude that NO2 gas has similar features as given above.

• CFCs
  • These compounds are non-flammable, tasteless and odourless, and chemically stable. 
  • These compounds are cause of Global warming.
• SO2
  • ​It is a colourless gas with a rotten egg odour.
  • It is also cause of Acid rain.
• SO3
  • ​Sulfur trioxide, is a colorless to white crystalline solid which will fume in air.
  • Vapor is pungent; like sulfur dioxide. Mist is odorless.
  • It is also cause of Acid rain.