A lake which is rich in organic waste may result in?

1.	increased population of aquatic organisms due to minerals
2.	drying of the lake due to algal bloom
3.	increased population of fish due to lots of nutrients
4.	mortality of fish due to lack of oxygen

The highest DDT concentration in aquatic food chain shall occur in?

1. phytoplankton

2. seagull

3. crab

4. eel

An increase in the concentration of the toxicant at successive trophic levels is known as:

1. Biomagnifications

2. Biodeterioration

3. Biotransformation

4. Biogeochemical cycling

Eutrophication of water bodies leading to the killing of fishes is mainly due to non-availability of:

1. Food

2. Light

3. Essential minerals

4. Oxygen

The zone of atmosphere in which the ozone layer is present is called:

1. Ionosphere

2. Mesosphere

3. Stratosphere

4. Troposphere

A scrubber in the exhaust of a chemical industrial plant removes:

1. Gases like sulphur dioxide

2. Particulate matter of the size 5 micrometer or above

3. Gases like ozone and methane

4. Particulate matter of the size 2.5 micrometer or less