Biochemical oxygen Demand value less than 5 ppm indicates a water sample to be : 

1. Highly polluted.

2. Poor in dissolved oxygen.

3. Rich in dissolved oxygen.

4. Not suitable for aquatic life.

Living in the atmosphere of CO is dangerous because it : 

1. Combines with O₂ present inside to form CO₂

2. Reduces organic matter of tissues.

3. Combines with haemoglobin and makes it incapable to absorb oxygen.

4. Dilutes the blood.

Photochemical smog formed in congested metropolitan cities mainly consists of : 

1. Ozone, SO₂, and hydrocarbons.

2. Ozone, PAN, and NO₂

3. PAN, smoke and SO₂

4. Hydrocarbons, SO₂, and CO₂

The oxygen present today in the atmosphere- 

1. Is a plant product.

2. Came from ozone.

3. Was present in the beginning.

4. Is produced by carbon dioxide.

Air pollution from the leakage of methyl isocyanate gas from the union carbide factory in Bhopal caused a major tragedy on:

1. Dec. 2, 1984

2. Dec 15, 1983

3. Dec.10, 1982

4. Dec. 4, 1988

Gas that is not a pollutant is : 

1. Carbon monoxide

2. Nitrogen peroxide

3. Carbon dioxide

4. Sulphur dioxide

The ‘thickness’ of Stratospheric Ozone layer is measured in/on:
1. Sieverts units
2. Dobson units
3. Melson units
4. Beaufort Scale

Which country has the greatest contribution for the hole formation in ozone layer?

1. Russia

2. Japan

3. USA

4. Germany

Which of the following is not one of the prime health risks associated with greater
UV radiations through the atmosphere due to depletion of stratospheric ozone?       

1. Damage to eyes
2. Increased liver cancer
3. Increased skin cancer.
4. Reduced Immune system

When rain is accompanied by a thunderstorm, the pH value of the collected rain water is :

1. Dependent upon the amount of dust in the air.

2. Slightly lower when rainwater is without a thunderstorm.

3. Slightly higher when the thunderstorm is not there.

4. Unaffected by the occurrence of thunderstorms.