Chemistry Miscellaneous Part-1

Total Questions: 42

21. In India, the use of carbofuran, methyl parathion, phorate, and triazophos is viewed with apprehension. These chemicals are used as: [I.A.S. (Pre) 2019]

(a) Pesticides in agriculture
(b) Preservatives in processed foods
(c) Fruit-ripening agents
(d) Moisturizing agents in cosmetics

Correct Answer: (a) Pesticides in agriculture

Solution:Carbofuran, methyl parathion, phorate, and triazophos are used as pesticides in agriculture. Based on the recommendation of the Anupam Verma Committee, the Union Ministry of Agriculture and Farmers Welfare banned 18 pesticides under the Pesticides (Prohibition) Order, 2018.

22. The Weedicide commonly used for paddy is: [U.P. Lower Sub. (Mains) 2015]

(a) DDT
(b) Dalapon
(c) 2,4-D
(d) Ammonium Sulfamate

Correct Answer: (c) 2,4-D

Solution:The weedicide commonly used for paddy is 2,4-D (2,4-Dichlorophenoxyacetic acid), a selective translocated herbicide commonly used to control broadleaf weeds without harming the crop itself.

23. 2,4-D is: [U.P.P.C.S. (Pre) 1999]

(a) An insecticide
(c) A fungicide
(c) A fungicide
(d) A herbicide

Correct Answer: (d) A herbicide

Solution:2,4-Dichlorophenoxyacetic acid (2,4-D) is a systemic herbicide used to control broadleaf weeds. It is a synthetic auxin (plant hormone) commonly used in laboratories for plant research and in plant cell culture media.

24. Dichloro-diphenyl-trichloroethane (DDT) is a: [U.P.P.C.S. (Pre) 2022]

(a) Non-biodegradable pollutant
(b) Biochemical pollutant
(c) Non-pollutant
(d) Biodegradable pollutant

Correct Answer: (a) Non-biodegradable pollutant

Solution:Dichlorodiphenyltrichloroethane (DDT) is an insecticide used in agriculture. It is an organic halogen that acts by disrupting the function of the nervous system and kills insects rapidly upon contact. DDT is harmful to all biota of the planet as it is non-biodegradable and tends to become more concentrated as it moves up the food chain. It is a fat-soluble chemical, accumulating in the fat deposits of the body. The United States banned the use of DDT in 1972. Some countries outside the United States still use DDT to control mosquitoes that spread malaria. DDT and its related chemicals persist for a long time in the environment and in animal tissues.

25. Which one of the following substances is a herbicide? [U.P. R.O./A.R.O. (Pre) 2017]

(a) Chlorpyrifos
(b) Carbendazim
(c) Quinolphos
(d) Butachlor

Correct Answer: (d) Butachlor

Solution:Butachlor is a herbicide of the acetanilide class. It is extensively used in the form of granules in rice farming.

26. Isotope C-14 is associated with: [R.A.S./R.T.S. (Pre) 1993]

(a) For cancer diagnosis
(b) Determining the age of the earth
(c) Determining the age of fossils
(d) For trailer technology

Correct Answer: (c) Determining the age of fossils

Solution:Isotope C-14 is used to determine the age of wood and bones (the time elapsed after the death of plants or animals), which is called Radio Carbon Dating. The half-life of Carbon-14 is 5,730 ± 40 years.

27. Which of the following archaeological samples is adopted to determine the age of firewood, bone, and shell? [I.A.S. (Pre) 1993]

(a) Uranium-238
(b) Argon-Isotopes
(c) Carbon-14
(d) Strontium-90

Correct Answer: (c) Carbon-14

Solution:

Carbon-14 (¹⁴ $C$ ) dating, or radiocarbon dating, is a radiometric dating method that uses the naturally occurring radioactive isotope of carbon to estimate the age of carbon-bearing materials up to about 50,000 to 60,000 years old. This includes organic materials like wood, bone, shell, and other fossils that were once part of living organisms.

28. Carbon dating is used to determine the age of: [M.P.P.C.S. (Pre) 1993]

(a) Trees
(b) Earth
(c) Fossils
(d) Rocks

Correct Answer: (c) Fossils

Solution:Carbon dating is primarily used for organic remains, which are often found as fossils. While it can date trees (if they are old enough as wood samples), its primary archaeological and paleontological application is for dating organic fossils. It cannot date the Earth or most rocks directly because they generally don't contain sufficient organic carbon from recent biological activity.

29. 'Radioactive dating' is a technique which can be used to measure: [U.P.P.C.S. (Pre) 2006]

(a) The age of rocks
(b) Composition of rocks
(c) Colour of rocks
(d) Weight of rocks

Correct Answer: (a) The age of rocks

Solution:Radioactive dating (also known as radiometric dating) is a general term for techniques that use the decay of radioactive isotopes to determine the age of geological or archaeological materials. While carbon dating is one type of radioactive dating for organic materials, other radioactive isotopes (like Uranium-Lead, Potassium-Argon, Rubidium-Strontium) are used to date much older materials like rocks and the Earth itself.

30. Which of the following methods is used for measuring the age of the earth? [U.P.P.C.S. (Pre) 1992]

(a) Carbon dating process
(b) Biotechnology Law
(c) Biological clock method
(d) Uranium process

Correct Answer: (d) Uranium process

Solution:Uranium-lead dating is one of the oldest and most refined methods to determine the age of the earth, decaying rocks, and bones. Clair Cameron Patterson, an American geochemist, pioneered studies of Uranium-lead radiometric dating methods. He is famous for having used these methods to obtain one of the earliest accurate estimates of the age of the earth.

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