Chemistry (Part-XII)

Total Questions: 50

11. The by-product of the soap industry is ______ . [C.P.O. S.I. 5.06.2016 (Shift-II) ]

(a) Caustic soda
(b) Glycerol
(c) Naphthalene
(d) Caustic potash

Correct Answer: (b) Glycerol

Solution:Sodium hydroxide (NaOH) is a white crystalline solid. It is soluble in water. Its aqueous solution is as smooth as soap. Sodium hydroxide (NaOH) is a combustible substance. It blisters on the skin, hence it is called 'burning soda'. It is used to make soap. On hydrolysis of oil or fat with caustic soda solution, soap and glycerol are formed. This process is called saponification of oil or fat.

12. Soaps are sodium salts of which of the following? [S.S.C. Online MTS (T-I) 18.09.2017 (Shift-III) ]

(a) Mineral acid
(b) Fatty acids
(c) Lactic acid
(d) Organic acids

Correct Answer: (b) Fatty acids

Solution:Soaps are fundamentally the alkali metal salts (most commonly sodium or potassium salts) of long-chain carboxylic acids, which are also known as fatty acids. These fatty acids are derived from the hydrolysis of fats and oils during the saponification process.

13. Which of the following is not true about X-rays? [S.S.C. Online Graduate Level (T-I) 29.08.2016 (Shift-I) ]

(a) have low penetrating power
(b) travel with the speed of light
(c) can be reflected or refracted
(d) can affect photographic plates

Correct Answer: (a) have low penetrating power

Solution:X-rays are a form of electromagnetic radiation with very high energy and short wavelengths. This high energy gives them high penetrating power, allowing them to pass through soft tissues but be absorbed by denser materials like bones, which is why they are used in medical imaging.

14. Device used for the detection and measurement of all types of radiation (Alpha, Beta and Gamma). [S.S.C. Online CHSL (T-I) 9.01.2017 (Shift-III) ]

(a) Geiger Counter
(b) Polarimeter
(c) Calorimeter
(d) Radiometer

Correct Answer: (a) Geiger Counter

Solution:A Geiger counter (or Geiger-Müller counter) is a well-known instrument used for detecting and measuring ionizing radiation, including alpha particles, beta particles, and gamma rays. It works by detecting the ionization produced when radiation passes through a gas-filled tube.

15. Which of the following produces the most solid waste? [S.S.C. Online Graduate Level (T-I) 2.09.2016 (Shift-III) ]

(a) Agriculture
(b) Nuclear Power Plants
(c) Manufacturing
(d) Packaging Industry

Correct Answer: (c) Manufacturing

Solution:While agriculture, nuclear power plants, and the packaging industry all produce waste, the manufacturing sector (including industries like metallurgy, chemicals, textiles, paper, etc.) is generally recognized as the largest generator of industrial solid waste globally due to the diverse range of processes, materials, and by-products involved.

16. Which among the following is false about alpha particles? [S.S.C. Online CHSL (T-I) 10.01.2017 (Shift-II) ]

(a) They have high ionizing power
(b) They have high penetrating power
(c) They have high kinetic energy
(d) They are positively charged Helium nuclei

Correct Answer: (b) They have high penetrating power

Solution:Alpha (α), beta (β), and gamma (γ) are radioactive radiation. In these, the alpha particle is the positively charged helium center, whose penetrating power is much less than that of beta (β) and gamma (γ) rays.

17. For what is the Radiocarbon dating technique used? [S.S.C. Online CHSL (T-I) 15.01.2017 (Shift-I) ]

(a) To estimate soil contamination
(b) To estimate the amount of water in fossils
(c) To estimate the age of fossils
(d) To estimate the quality of soil

Correct Answer: (c) To estimate the age of fossils

Solution:Radiocarbon dating (or Carbon-14 dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 to determine the age of carbonaceous materials up to about 50,000 to 60,000 years old. This makes it highly effective for dating archaeological artifacts, bones, wood, and other organic remains, including fossils.

18. Carbon dating means: [S.S.C. Online CPO SI (T-I) 09.11.2022 (Shift-I) ]

(a) A method to determine the density of fissile material.
(b) A method of calculating the remains of sulphur and nitrogen in hard rock.
(c) A method of calculating the age of very old objects by measuring the amounts of different forms of carbon in them.
(d) A method of determination of weight of a very old rock.

Correct Answer: (c) A method of calculating the age of very old objects by measuring the amounts of different forms of carbon in them.

Solution:A method of calculating the age of very old objects by measuring the amounts of different forms of carbon in them. Carbon dating, also known as radiocarbon dating, is a technique used to determine the age of organic materials up to 50,000 years old. It works by measuring the amount of radioactive carbon-14 in the sample and comparing it to the amount of stable carbon-12. The ratio between the two can be used to estimate the age of the material.

19. The chemical that is used to ripen mangoes is- [S.S.C. Online Graduate Level (T-I) 4.09.2016 (Shift-III) ]

(a) Calcium Sulphide
(b) Calcium Carbide
(c) Calcium Carbonate
(d) Calcium Chloride

Correct Answer: (b) Calcium Carbide

Solution:Calcium carbide (CaC₂) is commonly used in some regions for the artificial ripening of fruits, including mangoes. When calcium carbide comes into contact with moisture, it produces acetylene gas (C₂H₂), which acts as an artificial ripening agent, similar to the natural plant hormone ethylene. However, its use is often regulated or banned due to concerns about impurities (like arsenic) and health risks.

20. Which chemical is used for the artificial ripening of mangoes? [S.S.C. Online CHSL (T-I) 19.01.2017 (Shift-II) ]

(a) Sulfur dioxide
(b) Nitrous oxide
(c) Calcium carbide
(d) Phosphorous

Correct Answer: (c) Calcium carbide

Solution:Calcium carbide is used for ripening mangoes. Its chemical formula is CaC₂. When calcium carbide comes in contact with water or water vapor, acetylene gas (C₂H₂) is produced, which accelerates the ripening of fruits.

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