NEET UG CHEMISTRY Multiple Choice Questions (MCQs)

221. Which of the following compounds is most likely to undergo nucleophilic substitution?

• a) CH₃-CH₂-Cl
• b) CH₃-CH₂-CH₃
• c) CH₃-CF₃
• d) CH₃-CH₂-OH

Answer: a) CH₃-CH₂-Cl

222. What is the major product when iodoform (CHI₃) reacts with an alkyl group containing at least one methyl group?

• a) Formaldehyde
• b) Acetaldehyde
• c) Acetone
• d) Methanol

Answer: c) Acetone

223. Which of the following is the main environmental concern associated with DDT?

• a) It is carcinogenic
• b) It contributes to ozone depletion
• c) It is non-biodegradable
• d) It induces mutation in plants

Answer: c) It is non-biodegradable

224. Which of the following is a characteristic property of alkyl halides?

• a) High boiling point
• b) Strong nucleophilic substitution
• c) High reactivity towards nucleophiles
• d) No reactivity towards nucleophiles

Answer: c) High reactivity towards nucleophiles

225. What is the bond angle in the C-X bond of chloroform (CHCl₃)?

• a) 109.5°
• b) 120°
• c) 180°
• d) 90°

Answer: a) 109.5°

226. Which halogenated compound is commonly used as a solvent in laboratories and has harmful environmental effects?

• a) Chlorine
• b) Bromine
• c) Chloroform
• d) Iodine

Answer: c) Chloroform

227. What type of mechanism is involved in the substitution of halogens in alkyl halides?

• a) Free radical substitution
• b) Electrophilic substitution
• c) Nucleophilic substitution
• d) Addition reaction

Answer: c) Nucleophilic substitution

228. Which of the following is the mechanism of substitution in the reaction of alkyl halides with sodium hydroxide?

• a) SN1 mechanism
• b) SN2 mechanism
• c) Electrophilic addition
• d) Free radical substitution

Answer: b) SN2 mechanism

229. The stability of alkyl carbocations formed during nucleophilic substitution reactions is influenced by:

• a) The type of halogen
• b) The size of the halogen atom
• c) The availability of a lone pair of electrons
• d) The degree of alkyl substitution on the carbocation

Answer: d) The degree of alkyl substitution on the carbocation

230. Which of the following compounds is a halogenated hydrocarbon used as a solvent in laboratories?

• a) CH₃Cl
• b) CCl₄
• c) C₂H₅Br
• d) CH₃I

Answer: b) CCl₄

231. Which of the following reactions is a characteristic of alkenes when reacted with halogens?

• a) Electrophilic addition
• b) Nucleophilic substitution
• c) Free radical substitution
• d) Addition polymerization

Answer: a) Electrophilic addition

232. Which of the following is used as a refrigerant and has significant environmental concerns due to its contribution to ozone depletion?

• a) Chloroform
• b) Freons
• c) Iodoform
• d) DDT

Answer: b) Freons

233. What is the general effect of the halogen atom in alkyl halides on the molecule?

• a) Increases the basicity
• b) Decreases the boiling point
• c) Makes the molecule more polar
• d) Makes the molecule non-polar

Answer: c) Makes the molecule more polar

234. Which halogenated compound is commonly used in the preparation of antiseptics?

• a) Chlorine
• b) Iodoform
• c) Bromine
• d) Fluorine

Answer: b) Iodoform

235. Which of the following reactions is a characteristic of aryl halides?

• a) Nucleophilic substitution
• b) Electrophilic substitution
• c) Addition reactions
• d) Elimination reactions

Answer: b) Electrophilic substitution