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51.	What is the amount of oxygen required by bacteria to break down organic matter present in certain volume of sample of water is called?(a) Bacterial oxidation(b) Bacterial decomposition(c) Biochemical oxygen demand(d) Biological oxygen demandThis question was posed to me in semester exam.My question is taken from Environmental Chemistry in section Environmental Chemistry of Chemistry – Class 11
Answer» RIGHT option is (c) BIOCHEMICAL oxygen DEMAND For explanation I would say: The amount of oxygen required by bacteria to break down the organic matter PRESENT in a certain volume of a sample of water is called as Biochemical Oxygen Demand (BOD). The amount of BOD in water is a measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically. Clean water has BOD value less than 5 ppm whereas highly polluted water has BOD value of 17 ppm or more.

52.	Which of the following is not a gaseous air pollutant?(a) Ozone(b) Fumes(c) Hydrogen sulphide(d) CarbonThe question was asked in an international level competition.My doubt stems from Environmental Chemistry in division Environmental Chemistry of Chemistry – Class 11
Answer» Right option is (B) Fumes For explanation I would say: Fumes come under the category of particulate pollutants and not gaseous air pollutants. It CONSIST of solid particles in the FORM of suspension in the air. Such particulate pollutants can be released from DIFFERENT types of human activities. Fumes can be released from industries and other chemical plants as well. The other examples of particulate pollutants are dust, mist, smoke, smog, etc.

53.	When the pH of rain water is above 5.6, then it is called acid rain.(a) True(b) FalseI got this question in a national level competition.This intriguing question originated from Environmental Chemistry in section Environmental Chemistry of Chemistry – Class 11
Answer» The correct answer is (b) False The explanation is: On the pH scale, 7 is neutral; below 7 is said to be acidic and above 7 is said to be alkaline. Rain WATER NORMALLY has a pH of 5.6 due to the presence of H^+ions formed by the reaction of rain water with CARBON dioxide present in the atmosphere.When the pH of rain water falls below 5.6, then it is CALLED as acid rain. H2O (l) + CO2 (g)→ H2CO3 (aq) H2CO3 (aq) → H^+ (aq) + HCO3^–(aq)

54.	The amount of carbon dioxide should not cross the delicate proportion of which of the following?(a) 0.01%(b) 0.04%(c) 0.3%(d) 0.03%This question was addressed to me in an interview for job.My query is from Environmental Chemistry topic in division Environmental Chemistry of Chemistry – Class 11
Answer» Right option is (d) 0.03% The best explanation: The amount of carbon DIOXIDE OPTIMUM for the environment should be 0.03 per cent. If this per cent is crossed, then the natural greenhouse balance may GET disturbed since carbon dioxide is the MAJOR contributor to global warming. But, low concentrations are also not desirable. It can lead to kidney diseases. This condition can cause the body’s blood acid level to go up due to the LACK of insulin to digest sugars in the body.

55.	An average human being requires nearly 12-15 times more air than the food.(a) True(b) FalseI got this question in unit test.My enquiry is from Environmental Pollution topic in portion Environmental Chemistry of Chemistry – Class 11
Answer» Right answer is (a) True To explain I WOULD say: An average human being requires nearly 12-15 times more air than the food. So, EVEN small amounts of POLLUTANTS in the air become significant compared to similar levels present in the food. THEREFORE, the amount of people SUFFERING various diseases due to contaminants in air is more than that suffering due to contaminants in food.

56.	What is the full form of DDT?(a) Diphenyldichlorotrichloroethane(b) Dichlorodiphenyltrichloroethane(c) Dichlorodiphenyltriphenylethane(d) DichlorodiphenyltrichloroetheneThis question was addressed to me by my college director while I was bunking the class.Asked question is from Environmental Pollution topic in division Environmental Chemistry of Chemistry – Class 11
Answer» Correct ANSWER is (b) Dichlorodiphenyltrichloroethane Explanation: Explanation: The full form of DDT is dichlorodiphenyltrichloroethane. It is a colorless, tasteless, and almost odorless crystalline chemical compound. It was originally developed as an insecticide, but then, its USE was stopped due to its HARMFUL EFFECT on environment as well as on the living organisms. If EXPOSED to high concentrations, it can cause vomiting, seizures or tremors in human beings.

57.	Identify the degradable pollutant from the following.(a) Chemicals(b) Metals(c) Discarded vegetables(d) PlasticI got this question in a job interview.This is a very interesting question from Environmental Pollution topic in portion Environmental Chemistry of Chemistry – Class 11
Answer» Right option is (c) Discarded vegetables To EXPLAIN I WOULD say: Discarded vegetables are degradable pollutants. SINCE they are organic, they can be rapidly broken down by micro-organisms through natural processes. Chemicals, metals, and plastics are inorganic and they will slowly DEGRADE, thereby, remaining in an unchanged form in the environment for many decades.

58.	A substance, which causes pollution, is known as which of the following?(a) Pollutant(b) Carcinogen(c) Polluting element(d) IrritantThe question was asked in final exam.Query is from Environmental Pollution topic in chapter Environmental Chemistry of Chemistry – Class 11
Answer» Correct ANSWER is (a) Pollutant Best explanation: A substance, causing pollution, is called as a pollutant. Pollutants can be solid, liquid, or gaseous substances present in GREATER concentrations than in natural ABUNDANCE and are produced DUE to human activities or due to natural happenings. Carcinogens are substances, if exposed to, which can cause cancer. Irritants normally cause irritations to SKIN.