Dobson units are used to measure thickness of:
1. Ozone
2. Troposphere
3. CFCs
4. Stratosphere

Green house effect is:
1.  Gardening outside the house
2.  Global cooling
3.  Global warming
4.  Green colour house

Maximum DDT is present in birds feeding on:
1.  Fishes
2.  Meat
3.  Insects
4.  Seeds

Large-scale death of fish occurs in:
1.  Saline lake
2.  Oligotrophic lake
3.  Eutrophic lake
4.  Shallow lake

Concentration of DDT is highest in:
1.  Primary consumer
2.  Producers
3.  Top consumer
4.  Decomposers

Sewage purification is performed by:
1.  Microbes
2.  Fertilisers
3.  Antibiotics
4.  Antiseptics

Temperature variation in Pacific ocean in present time is called:
1.  Cyclone effect
2.  El Nino effect
3.  Greenhouse effect
4.  Gaudikov's effect

Besides CH₄ and CO₂, another green house gas is:
1.   SO₂
2.   NH₃
3.   N₂O
4.   CFC 

If $C{O}_2$ is absent in the atmosphere of the earth, then:
1.  Temperature will decrease
2.  Temperature will increase
3.  Plants will flourish well
4.  No effect

Consider the following statements (A-D) about organic farming:
 

Which of the above statements is correct?
1. (A) and (B) only 
2. (B), (C) and (D)
3. (C) and (D) only 
4. (B) and (C) only