Which of the following gases is not a greenhouse gas?

1.  CO

2.  O₃ 

3.  CH₄

4.  Water vapour

Photochemical smog occurs in warm, dry, and sunny climates. One of the following is not amongst the components of photochemical smog. Identify it:

1.  NO₂

2.  O₃

3.  SO₂

4.  Unsaturated hydrocarbon

The incorrect statements about classical smog among the following is:

Biochemical Oxygen Demand (BOD), is a measure of organic material present in water. BOD value less than 5 ppm indicates a water sample to be

1.  Rich in dissolved oxygen 

2.  Poor in dissolved oxygen

3.  Highly polluted

4.  Not suitable for aquatic life

Which of the following statement(s) is wrong?

Sewage containing organic waste should not be disposed in water bodies because it causes major water pollution. Fishes in such a polluted water die because of

1. Large number of mosquitoes

2. Increase in the amount of dissolved oxygen

3. Decrease in the amount of dissolved oxygen in water

4. Clogging of gills by mud

Which of the following statements about photochemical smog is wrong?

The gaseous envelope around the earth is known as atmosphere. The lowest layer of this is extended upto 10 km from sea level, this layer is

1. Stratosphere 

2. Troposphere

3. Mesosphere

4. Hydrosphere

Dinitrogen and dioxygen are main constituents of air but these do not react with each other to form dioxides of nitrogen because ______.

The pollutants which come directly in the air from sources are called primary pollutants. Primary pollutants are sometimes converted into secondary pollutants. Which of the following belongs to secondary air pollutants?

1.  CO

2. Hydrocarbon

3.  Peroxyacetyl nitrate

4.  NO