They act as barriers to sound pollution and also act as dust catchers.

Yes; fertilizers in water body can lower the DO of water body to zero.

It produces vehicles which can run on dual mode like petrol and CNG. This technology reduces consumption of fossil fuels and produces less environmental pollutants.

(i) CNG is better than petrol or diesel because it burns most efficiently and very little of it is left unburnt,
(ii) It is cheaper than petrol or diesel,
(iii) It cannot be siphoned off by thieves, and
(iv) It cannot be adulterated like petrol or diesel.

Nuclear fall out refers to settling down of radioactive particles from the air on to the land. From the soil, these are absorbed by plants, whence they reach the animals and humans via food chains.

The quantitative pollutants are materials that are normally present in the environment but are also added in large amounts by man, e.g., CO₂.

The two major causes other than anthropogenic causes of the loss of biodiversity are
(i) Alien species invasions When alien species are introduced unintentionally or deliberately in a habitat, some of them can cause decline or extinction of indigenous species.
(ii) Co-extinctions when a species becomes extinct, the plant and animal species associated with it, in an obligatory way, also become extinct.

Glaciation, melting of snow, eruption of large volcanoes, earthquakes, movement of continents, large meteorites falling on earth, drought, etc. could have triggered mass extinctions.

Amphibians are found in and near wetlands. Many wetlands are being filled up by human beings for habitation and other purposes. Loss of habitat of amphibians has greater vulnerability for amphibians.

The criteria that should be used in categorising a species as threatened are
(i) number of the members of the species are declining at an alarming rate.
(ii) Their habitat is being modified or destroyed.
(iii) Predator or poacher activities are increasing.