CBSE Questions for Class 11 Medical Chemistry Environmental Chemistry Quiz 10 - MCQExams.com

The water-gas shift reaction (WGSR) describes  the reaction of carbon monoxide and water vapour to form carbon dioxide and hydrogen (the mixture of carbon monoxide and hydrogen is known as water gas)

• Addition of phosphates and nitrates/fertilizers into water leads to nutrient enrichment which is also called as eutrophication. 
  
• This is a kind of water pollution, because excessive nutrients result in growth of plants and algae over water surface which consume oxygen present and obstructs the light from entering the water.
  

Ozone is an inorganic molecule. It is a pale blue gas with a distinctively pungent smell. In the environment ozone is known for its both harmful and useful effects.
Ozone present in stratosphere is useful as it act like shield and protect the earth from harmful UV-rays which can cause serious problems like skin cancer and decrease in level of photosynthesis. Ozone present in troposphere act as pollutant and have many deleterious effects. 

Therefore, the correct answer is option C.

• The pair of chemicals that maintain heat balance in troposphere are $$N_2 $$ and $$  O_2$$
  
• The troposphere is 70% $$N_2$$ and 21% $$O_2$$. The lower density of molecules higher up would not give us enough $$O_2$$ to survive.

The weedkiller 2,4,5-T contains significant levels of an impurity called dioxin which causes birth defects in human babies. 

This herbicide contained an equal mixture of two phenoxy acids, one of which produces an obligatory byproduct called 2,3,7,8-tetrachlorodibenzo-p-dioxin, otherwise known as TCDD or dioxin.

Correct Answer: Option C

Explanation:

·        BOD known as biochemical oxygen demand which is a parameter to measure the organic pollution as well as surface water.

·        PSCs known as polar stratospheric clouds are the medium via which reservoir chlorine compounds are transformed into ozone-depleting chlorine radicals. There are two types of PSCs: type 1 and type 2.

·        PCBs are a class of organic chemicals used in the production of plastics, as lubricants, in transformers, adhesives, and other applications. They are highly harmful to aquatic life and can last for a long time in the environment. They can build up in food chains and, at high concentrations, can cause hazardous side effects.

·        The oxygen equivalent of the organic matter content of a sample that is sensitive to oxidation by a powerful chemical oxidant is characterized as chemical oxygen demand (COD). As a result, BOD is a metric for water pollution.

Final Answer: The correct answer is $$C.$$

1. Photochemical smog consists of primary and secondary pollutants. Primary pollutants consist of nitrogen oxides and volatile organic compounds, whereas secondary pollutants consist of Peroxy acetyl nitrate and ozone.
2. Aromatic hydrocarbons containing two or more fused rings are called Polycyclic aromatic hydrocarbons. It is found that the number and position of certain groups such as methyl, hydroxide, cyanide, and methoxy in these compounds give rise to carcinogenicity.
3. IR active molecules such as $$HCl, CO,$$ and $$NO$$ absorb the radiation from the infrared region and causes global warming.
4. Dioxins are a group of chlorinated organic compounds that are formed in Waste incineration.