170. Which feedstocks qualify under India’s National Policy on Biofuels:
1 Cassava,
2 damaged wheat,
3 groundnut,
4 horse gram,
5 rotten potatoes,
6 sugar beet?
[UPSC CSE Prelims — 2020]
(A) 1, 2, 5 and 6 only
(B) 1, 3, 4 and 6 only
(C) 2, 3, 4 and 5 only
(D) All six
Answer: (A) 1, 2, 5 and 6 only
Explanation: The policy recognises a variety of sugar- and starch-rich materials for ethanol production, including cassava, damaged wheat, rotten potatoes and sugar beet. Oilseeds and pulse crops are not automatically included within this specific listed category. The correct combination is 1, 2, 5 and 6.
169. Which order did the given CGPSC question identify for contributions to the greenhouse effect?
[CGPSC Civil Service Prelims — 2020]
(A) CO₂ > CH₄ > CFCs > N₂O
(B) CH₄ > CO₂ > CFCs > N₂O
(C) CO₂ > CFCs > CH₄ > N₂O
(D) CO₂ > CH₄ > N₂O > CFCs
Answer: (D) CO₂ > CH₄ > N₂O > CFCs
Explanation: The examination key selected the listed ordering with carbon dioxide followed by methane, nitrous oxide and CFCs. Modern scientific comparisons depend on whether one measures atmospheric concentration, radiative forcing or warming potential; these quantities must not be confused. The item reproduces the historical answer key.
168. Which of these cleaning agents is a cationic detergent?
[NEET Phase 1 Chemistry — 2020]
(A) Sodium stearate
(B) Cetyltrimethylammonium bromide
(C) Sodium dodecylbenzene sulphonate
(D) Sodium lauryl sulphate
Answer: (B) Cetyltrimethylammonium bromide
Explanation: Cetyltrimethylammonium bromide is a quaternary ammonium salt whose surfactant head carries a positive charge. Sodium lauryl sulphate and sodium dodecylbenzene sulphonate have anionic heads. Sodium stearate is a conventional soap, not the cationic detergent specified in the paper.
167. Which one of the following is not a natural polymer?
[RPSC Senior Teacher Science — 04 Jul 2019]
(A) Teflon
(B) Starch
(C) Protein
(D) Cellulose
Answer: (A) Teflon
Explanation: Teflon, or polytetrafluoroethylene, is a synthetic polymer. Starch and cellulose are naturally occurring polysaccharides, while proteins are natural polymers of amino acids. Distinguishing naturally occurring macromolecules from manufactured polymers is central to basic polymer chemistry.
166. What are the monomer units of Glyptal?
[RPSC Senior Teacher Science — 04 Jul 2019]
(A) Urea and formaldehyde
(B) Phenol and formaldehyde
(C) Ethylene glycol and phthalic acid
(D) Ethylene glycol and terephthalic acid
Answer: (C) Ethylene glycol and phthalic acid
Explanation: Glyptal is a polyester resin made from ethylene glycol and phthalic acid through condensation polymerisation. Terephthalic acid with ethylene glycol instead forms PET-type polyester. Phenol and formaldehyde yield a different thermosetting polymer, Bakelite.
165. Which one of the following is a non-reducing sugar?
[RPSC Senior Teacher Science — 04 Jul 2019]
(A) Glucose
(B) Maltose
(C) Lactose
(D) Sucrose
Answer: (D) Sucrose
Explanation: Sucrose lacks a free anomeric hemiacetal or hemiketal because the anomeric centres of glucose and fructose are joined in its glycosidic bond. It therefore does not behave as a typical reducing sugar. Glucose, lactose and maltose can act as reducing sugars.
164. Which substances form the traditional composition of gunpowder?
[Kerala SET Paper 1 — Jul 2019]
(A) Aluminium nitrate, charcoal and sulphur
(B) Potassium nitrate, charcoal and sulphur
(C) Silver nitrate, charcoal and sulphur
(D) Charcoal and TNT
Answer: (B) Potassium nitrate, charcoal and sulphur
Explanation: Traditional black powder is identified in general chemistry by potassium nitrate, charcoal and sulphur as constituent substances. It is a historical explosive mixture. The test is about naming its components, not about proportions, mixing or practical application.
163. Which of the following is not a named explosive in the given tunnelling-material list?
[MPSC Assistant Engineer Civil Mains — 2019, Paper 2]
(A) PENT
(B) RDX
(C) TNT
(D) NTT
Answer: (D) NTT
Explanation: PETN, RDX and TNT are established names or abbreviations encountered in classifications of explosive materials. NTT is not a recognised standard substance in the question’s list. The item requires identifying terminology rather than predicting behaviour or handling characteristics.
162. Biogas consists primarily of which listed mixture?
[WBCS Prelims — 2019]
(A) Carbon monoxide, methane and hydrogen
(B) Carbon dioxide, methane and hydrogen
(C) Carbon monoxide, ethane and hydrogen
(D) Carbon dioxide, ethane and hydrogen
Answer: (B) Carbon dioxide, methane and hydrogen
Explanation: Biogas produced by anaerobic digestion is dominated by methane and carbon dioxide, with possible small amounts of hydrogen and hydrogen sulphide. Ethane is not a principal component. The methane content is responsible for the fuel’s practical heating value.
161. Which one of the following is an aerobic process?
[RPSC Senior Teacher Science — 18 Feb 2019]
(A) Lactic acid fermentation
(B) Glycolysis
(C) Alcoholic fermentation
(D) Acetic acid fermentation
Answer: (D) Acetic acid fermentation
Explanation: Acetic acid bacteria oxidise ethanol to acetic acid in the presence of oxygen, making this an aerobic process. Alcoholic and lactic acid fermentations commonly occur under anaerobic conditions, while glycolysis itself does not require molecular oxygen.
