Chemistry Miscellaneous Part-1

Total Questions: 42

1. In the year 2021, the Nobel Prize in Chemistry was awarded to: [Uttarakhand P.C.S. (Pre) 2021]

(a) Syukuro Manabe, Klaus Hasselmann & Giorgio Parisi
(b) David Julius & Ardem Patapoutian
(c) Benjamin List & David MacMillan
(d) Abdulrazak Gurnah

Correct Answer: (c) Benjamin List & David MacMillan

Solution:The Nobel Prize in Chemistry, 2021 was awarded jointly to Benjamin List and David W.C. MacMillan for the development of asymmetric organocatalysis. The Nobel Prize in Chemistry, 2022 was awarded jointly to Carolyn R. Bertozzi, Morten Meldal and K. Barry Sharpless for the development of click chemistry and bioorthogonal chemistry. Moungi G. Bawendi, Louis E. Brus and Aleksey Yekimov are awarded the Nobel Prize in Chemistry, 2023 for the discovery nd development of quantum dots.

2. The Nobel Prize in Chemistry, 2019 was awarded for the development of: [66th B.P.S.C. (Pre) 2020]

(a) LED
(b) LCD
(c) Lithium-ion batteries
(d) MRI
(e) None of the above/More than one of the above

Correct Answer: (c) Lithium-ion batteries

Solution:The Nobel Prize in Chemistry, 2019 was awarded to John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino for the development of lithium-ion batteries. The Nobel Prize in Chemistry, 2020 was awarded to Emmanuelle Charpentier and Jennifer A. Doudna for the development of a method for genome editing (CRISPR/Cas 9 genetic scissors).

3. Which of the following types of glass can cut off ultraviolet rays? [U.P.P.C.S. (Mains) 2021]

(a) Soda glass
(b) Pyrex glass
(c) Jena glass
(d) Crookes glass

Correct Answer: (d) Crookes glass

Solution:

Crookes glass is one of the several types of glasses designed to diminish the transmission of ultraviolet rays. It is used to make sunglasses.

Pyrex glass is a clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware.

Jena glass is a shock- and heat-resistant glass used in scientific and technological applications, especially in chemistry.

Soda-lime glass is produced on a large scale and used for bottles, drinking glasses, and windows.

4. Consider the following: [I.A.S. (Pre) 2023]

Aerosols
Foam agents
Fire retardants
Lubricants

In the making of how many of the above are hydrofluorocarbons used?

(a) Only one
(b) Only two
(c) Only three
(d) All four

Correct Answer: (c) Only three

Solution:Hydrofluorocarbons (HFCs) are potent greenhouse gases that were introduced as replacements for ozone-depleting substances (like CFCs and HCFCs).

Aerosols: HFCs are commonly used as propellants in various aerosol products.

Foam agents: HFCs are used as blowing agents in the production of foams (e.g., insulation foams).

Fire retardants: While some HFCs have been used in specialized fire suppression systems, their use as general fire retardants (additives to materials to make them less flammable) is not their primary application. Halons were more common for this, and newer alternatives are sought. However, some HFCs can be found in fire suppression.

Lubricants: HFCs are generally not used as lubricants. Lubricants are typically oils, greases, or other specialized compounds designed to reduce friction.

5. The ozone layer of the upper atmosphere is being destroyed by which of the following? [U.P. R.O./A.R.O. (Mains) 2017]

(a) Sulphur Dioxide
(b) Photo-chemical oxidants
(c) Chlorofluorocarbons
(d) Smog

Correct Answer: (c) Chlorofluorocarbons

Solution:When chlorine and bromine atoms make contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom of chlorofluorocarbon can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created.

6. Consider the following assertion and reason and select the correct answer from the code given below. [U.P.P.C.S. (Mains) 2013]

Assertion (A): Ozone kills microorganisms in water.
Reason (R): Ozone is not radioactive.

(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

Correct Answer: (b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).

Solution:

Ozone is made up of three oxygen atoms (O₃) having a "free radical" of oxygen. It will readily give up one atom of oxygen providing a powerful oxidizing agent which is toxic to most waterborne organisms such as bacteria, mold, and yeast spores, viruses, or harmful protozoans that form cysts. Ozone is not radioactive. Thus, both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

7. Which of the following is used in a fire alarm? [U.P. P.C.S. (Pre) 2020]

(a) Photocell
(b) Water
(c) Solar cell
(d) None of the above

Correct Answer: (a) Photocell

Solution:The photocell is used in fire alarms. A photocell is a technological application of the photoelectric effect. It operates on semiconductor photoconductivity, where light photons hitting the semiconductor free electrons to flow, decreasing the resistance. If smoke enters the chamber, it refracts the light beam, causing the alarm to sound.

8. Which gas is used in fire extinguishers? [M.P.P.C.S. (Pre) 1991]

(a) Carbon dioxide
(b) Hydrogen
(c) Oxygen
(d) Sulphur dioxide

Correct Answer: (a) Carbon dioxide

Solution:Carbon dioxide gas is used in fire extinguishers to control small fires, often in emergency situations. It works by displacing oxygen (smothering the fire) and cooling the fuel. It's effective for Class B (flammable liquids) and Class C (electrical) fires.

9. In the ordinary fire extinguisher, carbon dioxide is generated by the reaction of [Uttarakhand Lower Sub. (Pre) 2010]

(a) Limestone and dilute Sulphuric acid
(b) Marble powder and dilute Hydrochloric acid
(c) Sodium bicarbonate and dilute Sulphuric acid
(d) Magnesite and dilute Hydrochloric acid

Correct Answer: (c) Sodium bicarbonate and dilute Sulphuric acid

Solution:In the ordinary fire extinguisher, carbon dioxide is generated by the reaction of sodium bicarbonate and dilute sulphuric acid:

2NaHCO₃+H2₂SO₄→Na₂SO₄+2H₂O+2CO₂

10. Which one of the following compounds is used to make fireproof clothing? [U.P.P.C.S. (Mains) 2015]

(a) Sodium Sulphate
(b) Magnesium Sulphate
(d) Aluminium Sulphate
(c) Ferrous Sulphate

Correct Answer: (d) Aluminium Sulphate

Solution:Aluminium sulphate is used to prepare fireproof clothes.

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