Railway Science (Chemistry-Chemistry in Everyday life)

Total Questions: 63

11. Which of the following is a use of Plaster of Paris ? [RRC Group D 25/08/2022 (Morning)]

(i) Manufacture of glass, soap and paper
(ii) As a cleaning agent for domestic purposes
(iii) Making toys, materials for decoration and for making surfaces smooth (iv) For baking

Correct Answer: (d) Only iii
Solution:

Plaster of Paris (CaSO₄ . 1/2H₂O) - prepared by heating calcium sulfate dihydrate, or gypsum (CaSO₄ .2H₂O) at 393K. It is a white powder, and has a very remarkable property of setting into a hard mass on wetting with water. Uses - Used for setting fractured bones, dentistry, Making toys, decorative materials, cheap ornaments, cosmetics, black-board, chalk, etc as fire-proofing material, sealing air-gaps in apparatus in labs.

12. Consider the below statements and identify the correct answer. [RRC Group D 25/08/2022 (Afternoon)]

Statement-I: The chemical formula for baking soda is CaSO₄ . 1/2H₂O
Statement-II: Baking soda is used for making toys, materials for decoration and for making surfaces smooth

Correct Answer: (d) Both the statements are false.
Solution:

Baking Soda (NaHCO₃) - Sodium bicarbonate. Uses - relief to acidity in the stomach, in fire extinguishers, Acts as a pesticide, in baking industries, in ear drops, cosmetics and personal care products.

13. Consider the below statements and identify the correct answer: [RRC Group D 25/08/2022 (Evening)]

Statement I: Graphite is bad conductors of electricity.
Statement II: In Graphite, each carbon atom is bonded to three carbon atoms in the same plane giving a hexagonal array.

Correct Answer: (a) Statement II is correct, and Statement I is incorrect.
Solution:

Graphite structure is formed by the hexagonal arrays being placed in layers one above the other. It has a giant covalent structure in which each carbon atom forms three covalent bonds with other carbon atoms. It is also a good conductor of electricity.
Uses - In pencils, lubricants, crucibles, foundry facings, polishes, arc lamps, batteries, brushes for electric motors, and cores of nuclear reactors.

14. Which of the following is the correct set of raw materials for washing soda preparation ? [RRC Group D 25/08/2022 (Evening)]

Correct Answer: (d) 𝑁𝑎𝐶𝑙, 𝑁𝐻₃ , 𝐶𝑂₂
Solution:

Washing Soda - Solvay Process is used for the preparation of sodium carbonate decahydrate (Na₂CO₃. 10H₂O). Properties - crystalline solid (white in color) and basic in nature. Uses - Laundry, making glasses etc.

15. What compounds are required for the manufacture of baking soda ? [RRC Group D 26/08/2022 (Evening)]

Correct Answer: (c) Common salt, Carbon dioxide and Ammonia
Solution:

Baking soda is the common name of sodium bicarbonate (NaHCO₃). Solvay process is used for the production of sodium bicarbonate and sodium carbonate industrially.
Uses - ingredient in baking powder, in effervescent salts and beverages, and as a constituent of dry-chemical fire extinguishers.

16. Baking powder is a mixture of: [RRC Group D 29/08/2022 (Evening)]

Correct Answer: (d) baking soda and mild edible acid
Solution:

It is a dry chemical leavening agent. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch.

17. Aashi, by mistake used an unknown solution to clean her clothes, in place of detergent. Her clothes faded. The solution could be: [RRC Group D 01/09/2022 (Evening)]

Correct Answer: (b) bleaching powder
Solution:

Bleach is a specific type of laundry aid that removes stains from clothing, but it also removes/fades the color of the clothes. Bleach creates a chemical reaction with a stain that breaks it down and removes it from clothing. Bleach also has a whitening and brightening effect on white clothing.
Bleaching powder is a pale yellowish powder existing with a strong smell of chlorine. It is soluble in water but due to the presence of impurities, we never observe a clear solution. Its chemical formula is CaOCl₂ with its chemical name Calcium hypochlorite.

18. Consider the below statements and identify the correct answer. [RRC Group D 02/09/2022 (Afternoon)]

Statement-I: The chemical formula for baking soda is NaHCO₃.
Statement-II: It is used in soda-acid fire extinguisher.

Correct Answer: (a) Both the statements are true.
Solution:

Sodium bicarbonate / Baking soda (NaHCO₃) - It is a salt composed of a Sodium cation and a bicarbonate anion.The chemicals used in Soda acid fire extinguishers are Sodium bicarbonate and Sulphuric acid. When they are used the gas evolved is Carbon dioxide,which does not support combustion.

19. When baking soda is heated it converts into________, water, and carbon dioxide. [RRC Group D 02/09/2022 (Evening)]

Correct Answer: (d) sodium carbonate
Solution:

The chemical equation is : 2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O. Baking soda is also known as Sodium bicarbonate. It is basic in nature. Reduces the acidity in the stomach. Used in the process of washing as a water softener.

20. Toothpaste is generally ________ in nature. [RRC Group D 05/09/2022 (Morning)]

Correct Answer: (d) basic
Solution:

Bacteria present in the mouth produce acids by degradation of sugar and food particles that remain in the mouth after eating.
Tooth decay can occur if the pH drops below 5.5. Toothpastes should be made above pH 7 so that they neutralize any acid formed in the mouth.