31 Year NEET Previous Year Questions: Environmental Chemistry (Old NCERT) - NEET MCQ

Green house gases such as CO₂, ozone, methane, the chlorofluoro  carbon compounds and water vapour form a thick cover around the earth which prevents the IR rays emitted by the earth to escape. It gradually leads to increase in temperature of atmosphere.

CO and oxides of Nitr ogen ar e poisnous gases present in automobile exhaust gases.

Green chemistry may be defined as the programme of developing new chemical products and chemical processes or making improvements in the already existing compounds and processes so as to make less harmful to human health and environment. This means the same as to reduce the use and production of hazardous chemicals. i.e. correct answer is option (b).

The ideal value of D.O for growth of fishes is 8 mg/ℓ . 7mgℓ is desirable range, below this value fishes get susceptible to desease. A value of 2 mg/ℓ or below is lethal for fishes.

The oxidised hydrocarbons and ozone in presence of humidity cause photochemical smog.
Hydrocarbons + O₂, NO₂, NO, O, O₃ → Peroxides, formaldehyde, peroxyacetylnitrate (PAN), acrolein etc.
It is oxidising in nature and causes irritation to eyes, lungs, nose, asthamatic attack and damage plants.

Based on the features given above the gas must be SO₂ 

Acid rain is the rain water containing sulphuric acid and nitric acid which are formed from the oxides of sulphur and nitrogen present in the air as pollutants and rain water has a pH of 4-5.