2nd Year NotesChemistry class 12th

2nd Year Chemistry Chapter 16 (Environmental Chemistry)

2nd Year Chemistry Chapter 16 (Environmental Chemistry) Short And Simple Question And Answer

Q1.What are the components of the environment?

Ans: Environment is consisted of the following four components:-

I. Atmosphere

ii. Hydrosphere

iii. Lithosphere iv.Biosphere/Ecosphere

Q2.What is lithosphere? Give its composition?

Ans: The Lithosphere consists of the rigid rocky crust of the earth. The lithosphere is composed of 46.6% oxygen, 27.72% silicon, 8.13% aluminum, and 5% Fe and the rest are some other metals.

Q3.What is ecosphere?

Ans: It is the component of the environment which includes the area of the earth that can support life. Some of the areas are the atmosphere, rivers, solid sediments, lakes, oceans, etc.

Q4.What are the primary air pollutants?

Ans: The primary pollutants of air are:-

I. Gases such as oxides of nitrogen, oxides of Sulphur, volatile organic compounds, radioactive substances, CO, etc.

ii. Automobile exhausts.

iii. Industrial waste effluents.

Q5.What are the secondary air pollutants?

Ans: The secondary air pollutants are N2O, HF, PAN, aldehydes, ketones, H2CO3, H2SO4, O3, etc.

Q6.CO is a quiet killer. Justify?

Ans: CO is quite a killer because it binds with haemoglobin which results in a decrease in oxygen-carrying capability. Eventually, death may occur if the exposure to CO is for a longer period.

Q7.What happens to the human body, when it is exposed to CO for a longer time?

Ans: When the human body is exposed to CO for a longer time, it creates the following problems:-

I. Fatigue

ii. Headache

iii. Unconsciousness

iv. Eventual death

Q8.What are the adverse effects of acid rain on earth?

Ans: The adverse effects of acid rain on Earth are:-

I. Acid rain makes the soil, rivers, and lakes slightly acidic.

ii. Leaching occurs due to the acidic pH of the soil which leaches the metals like Al, Pb, Hg, etc.

Q9.What is reducing smog?

Ans: A smog contains a higher concentration of SO2 and has a reducing property is known as reducing smog. The main sources of reducing smog are the combustion of coal and the chemical reactions of pollutants in the air.

Q10.What is oxidizing/photochemical smog?

Ans: A smog that contains higher concentration of agents like O3, NOx, and hydrocarbons and has oxidizing properties is called oxidizing or photochemical smog. It is yellowish brown, grey, hazy, and has an unpleasant odor.

Q10.What is BOD?

Ans: The value of biological oxygen demand (BOD) is the amount of oxygen that is consumed due to biological oxidation of dissolved organic matter in the given sample of water. It is measured experimentally by calculating the concentration of oxygen at the beginning and the end of 5 days period.

Q11.What is COD?

Ans: The value of chemical oxygen demand (COD) is the amount of oxygen that is consumed due to chemical oxidation of dissolved organic matter in the given sample of water. It can be determined directly by the addition of dichromate ions in water. The organic matter in water is oxidized while the remaining dichromate ions are determined titrimetrically.

Q12.What are the various stages of water purification?

Ans: There are four stages to purify raw water:-

I. Aeration

ii. Coagulation

iii. Precipitation and removal of solid matter

iv. Chlorination

Q13.What are the harmful effects of chlorination of water?

Ans: The harmful effects of chlorination of water are:-

I. The chlorination of water produces NCl3, which is a powerful eye irritant. Cl2 + H2O HCl + HClO
NH3 + 3HOCl NCl3 + 3H2O

ii. Chlorinated water may cause bladder and rectal cancer.

iii. If humic acid is present in water then chlorine combines with humic acid to form CHCl3, which is a liver carcinogen.

Q14.Define incineration?

Ans: The waste treatment process in which waste is heated at high temperatures ranging
from 900 to 1000 ̊C is called incineration.

Q15.How many ways are there for recycling plastics?

Ans: Plastics are recycled in three ways:-

I. Reprocessing

ii. Depolymerization

iii. Transformation

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