All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 644 of 686
- A. Overall mass of an isobar
- B. It is a fractional mass.
- C. It is molar mass of Ne
- D. The average atomic mass of Ne
Explanation: The atomic mass of an element like Neon (Ne) is typically expressed as an average atomic mass because neon exists as a mixture of…
Correct answer: The average atomic mass of Ne- A. Dry Ether
- B. Alcohol
- C. CS2
- D. CCl4
Explanation: Explanation:Grignard reagents are prepared by the reaction of magnesium metal with alkyl halides in the presence of dry ether.
Correct answer: Dry Ether- A. 1-Bromo-1-chloro-2, 2, 2-trifluoroethane
- B. 2-Bromo-2-chloro-1, 1, 1-trifluoroethane
- C. 1, 1, 1-Trifluoro-2-bromo-2-chloroethane
- D. 2-Chloro-2-bromo-1, 1, 1-trifluoroethane
Explanation: 2-Bromo-2-chloro-1,1,1- trifluoroethane is the IUPAC name for halothanes that are used in hospitals as an anaesthetic.
Correct answer: 2-Bromo-2-chloro-1, 1, 1-trifluoroethane- A. 1-Chloro-2-methylpropane
- B. 1-Chloro-2-methylbutane
- C. Isobutyl chloride
- D. 2-Methyl-3-chloropropane
Explanation: There are 3 carbons in a chain, Cl group is bonded to the 1st carbon and methyl is bonded to the 2nd carbon.
Correct answer: 1-Chloro-2-methylpropane- A. 4-methyl-6-chloro heptane
- B. 2-chloro-4-methyl heptane
- C. 2-chloro-4-n propyl hexane
- D. 2-chloro-4-n propyl pentane
Explanation: The longest carbon chain is 7 carbons long and has only single carbon-carbon bonds hence heptane.The numbering would favour chloro group…
Correct answer: 2-chloro-4-methyl heptane- A. Cl-CH2-CH2-Cl
- B. Cl-CH2-CH2-Br
- C. CF3-CHCl-Br
- D. Br-CH2-CH2-Br
Explanation: The following is the structure of halothane.
Correct answer: CF3-CHCl-Br- A. Primary alkyl halides
- B. Secondary alkyl halides
- C. Tertiary alkyl halides
- D. Quaternary alkyl halides
Explanation: Non-pentyl chloride is the primary alkyl halide because in it, Chlorine atom is linked to a primary carbon atom.
Correct answer: Primary alkyl halides- A. Cl, Br, I, F
- B. F, CI, Br, I
- C. Br, I, F, CI
- D. I, F, Cl, Br
Explanation: The correct reactivity order of alkyl halides is R-F < R-Cl < R-Br < R-I because the C-F bond is the strongest (making fluorine the least…
Correct answer: F, CI, Br, I- A. Propane
- B. Butane
- C. Methane
- D. Ethane
Explanation: Explanation:The reaction is a typical Grignard reagent hydrolysis reaction where the Grignard reagent (CH3CH2MgBr) reacts with water to…
Correct answer: Ethane- A. Nucleophilic addition
- B. Electrophilic addition
- C. Electrophilic substitution
- D. Nucleophilic substitution
Explanation: It is an example of nucleophilic addition. The CN- ion has a negative charge and it is attracted to a positive charge so CN- is a…
Correct answer: Nucleophilic addition- A. Nucleophilic addition
- B. Nucleophilic substitution
- C. Electrophilic addition
- D. Addition elimination
Explanation: This reaction is called an addition-elimination reaction since a water molecule is eliminated from the reaction whereas the lone pair of…
Correct answer: Addition elimination- A. n-butane
- B. Propane
- C. Iso-butane
- D. Alcohol
Explanation: Explanation:Alkanes are produced when grignard reacts with:Water Ammonia AlcoholAs a result, n-butane will be produced in the above…
Correct answer: n-butane- A. Gets inverted
- B. Remains same
- C. Depends upon the carbon atom
- D. Depends upon the electronegativity of halide
Explanation: A is correct as during SN2 reaction, alkyl halide molecule gets inverted.B is incorrect as during SN2 reaction, alkyl halide doesnt stay…
Correct answer: Gets inverted- A. H2O at room temperature
- B. Ethanol, heat
- C. KOH in alcohol
- D. Dilute NaOH(aq) warm
Explanation: The given reaction is an example of alkaline hydrolysis or nucleophilic substitution reaction in which a halogen atom in an alkyl halide…
Correct answer: Dilute NaOH(aq) warm- A. NO2
- B. NH3
- C. NO2+
- D. NH4+
Explanation: A nucleophile is electron-rich species and donates electron pairs to electron-deficient species. Therefore, ammonia (NH3) is a nucleophile.
Correct answer: NH3- A. Breakage of covalent bond
- B. Formation of carbocation
- C. Transition state
- D. Attack of nucleophile
Explanation: The nucleophile has a negative / partially negative charge and it readily attacks the carbocation in SN1 reactions (which has a positive…
Correct answer: Attack of nucleophile- A. Nucleophiles
- B. Cations
- C. Free radicals
- D. Anions
Explanation: A nucleophile is a chemical species that donates an electron pair to form a chemical bond in relation to a reaction.
Correct answer: Nucleophiles- A. Primary carbocation
- B. Secondary carbocation
- C. Tertiary carbocation
- D. Methyl carbocation
Explanation: Methyl Carbocation (CH₃⁺)Structure: Only has one carbon atom, with no alkyl groups to stabilize the positive charge.Stability: Least…
Correct answer: Methyl carbocation- A. Primary>secondary>tertiary
- B. Tertiary>secondary>primary
- C. Secondary>primary>tertiary
- D. Primary>tertiary >secondary
Explanation: Tertiary > Secondary > Primary (Correct)Explanation: Tertiary carbocations are the most stable due to inductive and hyperconjugation…
Correct answer: Tertiary>secondary>primary- A. SN1
- B. SN2
- C. E1
- D. E2
Explanation: In organic chemistry, the reaction involving the simultaneous breaking of a carbon-halogen bond (-C-X) and the formation of a…
Correct answer: SN2