210. Trinitrotoluene is used for which purpose?
[MP Patwari Group 2 Sub Group 4 — 24 Apr 2023, Shift 2]
(A) As an explosive
(B) As an abrasive
(C) To fuse two metals
(D) To melt metals
Answer: (A) As an explosive
Explanation: Trinitrotoluene, abbreviated TNT, is an organic nitro compound used as an explosive material. It is not ordinarily classified as an abrasive, a metal-bonding agent or a metal-melting substance. The item tests recognition of a compound’s general use.
209. Which compound–melting point pair is correct?
I. Acetic acid—290 K.
II. Ethanol—156 K.
[SSC CGL Tier-I — 27 Jul 2023, Shift 3]
(A) Only I
(B) Both I and II
(C) Neither I nor II
(D) Only II
Answer: (B) Both I and II
Explanation: Pure acetic acid freezes near 16.6°C, equivalent to about 290 K, whereas ethanol melts around minus 114°C, roughly 159 K. Many school references round ethanol’s melting point close to 156 K. Both exam-specified pairs were treated as correct.
208. Which class of organic compounds contains the –OH functional group?
[SSC CGL Tier-II — 03 Mar 2023]
(A) Alcohol
(B) Ethane
(C) Ketone
(D) Aldehyde
Answer: (A) Alcohol
Explanation: An alcohol has a hydroxyl group, –OH, bonded to a saturated carbon atom. Ethane is an alkane without oxygen; ketones contain an internal carbonyl group and aldehydes have a terminal carbonyl group. The functional group governs typical chemical reactions.
207. What is the approximate proportion of methane in cow-dung biogas?
[WBCS Mains (Science) — 2023]
(A) 30%
(B) 40%
(C) 50%
(D) 60%
Answer: (D) 60%
Explanation: Cow-dung biogas commonly contains about 55–65 percent methane, with most of the remainder being carbon dioxide and traces of other gases. Methane provides the main combustible component, explaining why the gas is useful for cooking and rural energy generation.
206. Which of these tranquilising medicines is a barbiturate?
[NEET Chemistry — 2023]
(A) Meprobamate
(B) Valium
(C) Veronal
(D) Chlordiazepoxide
Answer: (C) Veronal
Explanation: Veronal is a historical name for barbital, one of the earliest barbiturate sedatives. Valium and chlordiazepoxide are benzodiazepines, while meprobamate is a carbamate anxiolytic. Recognising the underlying heterocyclic or functional-group frameworks distinguishes these related pharmaceutical categories.
205. Complete the anaerobic respiration reaction: Glucose → ______ + carbon dioxide + energy.
[RRB Group D — 11 Oct 2022, Shift 1]
(A) Pyruvate
(B) Water
(C) Lactic acid
(D) Ethanol
Answer: (D) Ethanol
Explanation: In alcoholic fermentation, yeast enzymes convert glucose through intermediate steps into ethanol and carbon dioxide, releasing some usable energy. Lactic acid instead arises in a different anaerobic pathway. Fermentation is an important biological production route for ethanol.
204. Which of the following compounds contains only one carbon–carbon single bond?
[RRB Group D — 30 Sep 2022, Shift 2]
(A) Ethane
(B) Propane
(C) Butane
(D) Methane
Answer: (A) Ethane
Explanation: Ethane contains two carbon atoms connected by exactly one carbon–carbon single bond. Propane has two such bonds, butane has three, and methane has only one carbon atom and therefore no carbon–carbon bond at all.
203. The general formula CnH2n−2 represents:
[RRB Group D — 27 Sep 2022, Shift 2]
(A) Alkyne
(B) Alkene
(C) Alkane
(D) Acyclic compound
Answer: (A) Alkyne
Explanation: Open-chain alkynes containing one triple bond commonly follow CnH2n−2. Alkenes with one double bond follow CnH2n, while alkanes follow CnH2n+2. These formulas express differences in hydrogen saturation for comparable carbon chain lengths.
202. Why do typical carbon compounds not conduct electricity in the molten state?
[RRB Group D — 27 Sep 2022, Shift 2]
(A) Their bonding generally does not form mobile ions
(B) They are ionic
(C) They are non-covalent
(D) Their bonds form mobile ions
Answer: (A) Their bonding generally does not form mobile ions
Explanation: Most simple molecular carbon compounds are covalently bonded and do not generate freely moving ions on melting. Electrical conduction requires mobile charged particles. Graphite and certain other carbon-containing substances are exceptions, so the question refers to typical molecular organic compounds.
201. Carbon compounds linked by only single carbon–carbon bonds are known as:
[RRB Group D — 27 Sep 2022, Shift 1]
(A) Both saturated and unsaturated
(B) Neither saturated nor unsaturated
(C) Saturated compounds
(D) Unsaturated compounds
Answer: (C) Saturated compounds
Explanation: Saturated carbon compounds contain only single carbon–carbon bonds and have no carbon–carbon double or triple bonds. By contrast, unsaturated hydrocarbons contain multiple bonds and commonly undergo addition reactions. Alkanes are typical examples of saturated hydrocarbons.
