220. What is the chemical name of the compound responsible for the cooling sensation in mint leaves?
[SSC MTS — 04 Nov 2024, Shift 3]
(A) Ethanol
(B) Menthol
(C) Caffeine
(D) Capsaicin
Answer: (B) Menthol
Explanation: Menthol is an organic compound found in mint oils. It activates cold-sensitive receptors, creating a cooling sensation without necessarily reducing temperature. Caffeine is a stimulant, capsaicin produces a hot sensation, and ethanol is a simple alcohol.
219. What is the primary acid found in citrus fruits such as oranges and lemons?
[SSC MTS — 22 Oct 2024, Shift 2]
(A) Lactic acid
(B) Tartaric acid
(C) Citric acid
(D) Acetic acid
Answer: (C) Citric acid
Explanation: Citric acid is a naturally occurring organic tricarboxylic acid responsible for much of the tart flavour of citrus fruits. It is used in foods and beverages as an acidulant. It differs from ascorbic acid, which is vitamin C.
218. Which organism is used in the bread and alcohol industries?
[SSC MTS — 22 Oct 2024, Shift 1]
(A) Clostridium
(B) Nitrobacter
(C) Yeast
(D) Penicillium
Answer: (C) Yeast
Explanation: Yeast ferments sugars anaerobically to generate ethanol and carbon dioxide. Carbon dioxide makes bread dough rise, while ethanol is the desired product in alcoholic fermentation. This biological process provides an important industrial route to a familiar organic alcohol.
217. Which gas is released when vinegar and baking soda are combined, inflating a balloon?
[SSC MTS — 08 Oct 2024, Shift 2]
(A) Carbon dioxide
(B) Hydrogen
(C) Oxygen
(D) Nitrogen
Answer: (A) Carbon dioxide
Explanation: Acetic acid in vinegar reacts with sodium hydrogen carbonate in baking soda to release carbon dioxide, alongside water and sodium acetate. The gas expands and inflates the balloon. This demonstrates a gas-evolving acid–hydrogen carbonate reaction.
216. Which reaction forms glucose pentaacetate when glucose reacts with acetic anhydride?
[SSC CHSL — 05 Jul 2024, Shift 3]
(A) Reduction
(B) Addition of ketone
(C) Oxidation
(D) Acetylation of glucose
Answer: (D) Acetylation of glucose
Explanation: Glucose contains five hydroxyl groups capable of being acetylated. Reaction with acetic anhydride gives glucose pentaacetate. This is a modification of hydroxyl groups rather than reduction or oxidation and illustrates an important transformation in carbohydrate chemistry.
215. What does RDX stand for, according to the given options?
[UP Police Constable Re-exam — 30 Aug 2024, Shift 2]
(A) Research Department Expansion
(B) Research Department Explosive
(C) Research Development Explosive
(D) Raw Detonation Explosive
Answer: (B) Research Department Explosive
Explanation: Research Department Explosive is a commonly given expansion of RDX in general-knowledge examinations. The substance is also known as cyclonite or hexogen. Such naming questions concern identification of an energetic compound, not its synthesis or use.
214. What is the full form of TNT?
[OSSSC Forest Guard — 03 May 2024, Shift 2]
(A) Trinitrotoxin
(B) Trinitrotetra
(C) Trinuetrontoluene
(D) Trinitrotoluene
Answer: (D) Trinitrotoluene
Explanation: TNT is the conventional abbreviation for trinitrotoluene, an aromatic organic compound known as an explosive. The name points to a toluene-derived structure bearing three nitro groups. The question asks only for recognition of its chemical name.
213. What is the molecular formula of the first member of the alkene series?
[RRB JE CBT-I — 16 Dec 2024, Shift 3]
(A) C₅H₁₀
(B) C₂H₄
(C) C₃H₆
(D) C₄H₆
Answer: (B) C₂H₄
Explanation: Ethene, C₂H₄, is the simplest stable alkene and contains a carbon-carbon double bond. Open-chain monoalkenes generally follow CnH₂n. At least two carbon atoms are needed to form a carbon-carbon double bond, so methane has no corresponding one-carbon alkene.
212. In which Madhya Pradesh district is a polymer-manufacturing factory located?
[MPPSC Assistant Professor (Geography Paper II) — 04 Aug 2024]
(A) Betul
(B) Chhindwara
(C) Rewa
(D) Neemuch
Answer: (B) Chhindwara
Explanation: Chhindwara is the district identified in the examination as hosting a polymer manufacturing facility. Polymers are large molecules made from repeating structural units and underpin products such as plastics, fibres and elastomers. This question tests industrial geography related to polymer production.
211. Which of the following is not a natural fibre?
[SSC CGL 2022 Tier-II JSO paper — held 04 Mar 2023]
(A) Linen
(B) Cotton
(C) Rayon
(D) Jute
Answer: (C) Rayon
Explanation: Rayon is a man-made regenerated cellulose fibre, produced by processing natural cellulose chemically. Linen, cotton and jute are obtained directly from plant sources. Rayon is often described as semi-synthetic because its raw material is a natural polymer.
