All Free Chemistry MCQs with Answers
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11281. What is required other than anhydrous AICI3 when toluene is prepared by Friedal craft reaction
- A. C6H6 + CH3Cl
- B. C6H6
- C. C6H5C2H5
- D. C6H5Cl & CH3Cl
Explanation: In the Friedel-Crafts alkylation reaction to prepare toluene, anhydrous aluminum chloride (AlCl3) acts as a catalyst.
Correct answer: C6H6 + CH3Cl- A. HSO-
- B. SO2
- C. SO3
- D. H+
Explanation: The electrophile generated during the sulfonation of benzene by H2SO4 is SO3.
Correct answer: SO3- A. C3H7O-
- B. SCN-
- C. H2C+
- D. NH3
Explanation: H2C+ is a carbocation, which is an electron-deficient species i.e. an electrophile.
Correct answer: H2C+- A. Addition
- B. Elimination
- C. Free radical substitution
- D. Nucleophilic substitution
Explanation: Free radical substitution) - Correct: Halogenation of alkanes follows a free radical chain mechanism, initiated by UV light.
Correct answer: Free radical substitution- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The reactivity of alkenes towards the addition of bromine can be determined by the presence of electron-donating or electron-withdrawing…
Correct answer: Option C- A. Pentene >butene>propene
- B. Butene>ethene>propyne
- C. Propene>butene> pentene
- D. None of these
Explanation: Reactivity of alkenes is inversely proportional to the no. of carbon atoms. As the no.
Correct answer: Propene>butene> pentene- A. Both are highly ionic
- B. One is oxidising and the other is reducing
- C. One of the step is endothermic in both the cases
- D. All the steps are exothermic in both the cases
Explanation: HI and HCl do not do this for energetic reasons. The addition of Cl and I radicals to alkanes in an anti-Markovnikov fashion is an…
Correct answer: One of the step is endothermic in both the cases- A. Hydrolysis of phenyl magnesium iodide - Benzene
- B. y- Isomer BHC - Lindane
- C. (4n+2)pie rule - Aromaticity
- D. Trimerisation of propyne - Mesitylene
Explanation: Option A suggests that hydrolysis of phenyl magnesium iodide results in the formation of benzene. However, this is not correct.
Correct answer: Hydrolysis of phenyl magnesium iodide - Benzene- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The rate of Hydrogenation of an alkene decreases with increasing alkyl substitution on C = C.21.
Correct answer: Option A- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Attack of Br0 free radical on tertiary carbon is thermodynamically more favoured, leading to the formation of tertiary free radical, which…
Correct answer: Option B- A. Reaction of free radical with free radical
- B. Formation of two free radicals
- C. Consumption as well as production of another free radical
- D. Reaction between two molecules
Explanation: Propagation step involvesi) Attack of free radical on the molecule ii) Homolytic fission in the molecule iii) Bond formation.iv) Formation…
Correct answer: Consumption as well as production of another free radical- A. CI2→ 2CI
- B. CH4 +CI → CH3 +HCI
- C. CI2CH+Ci → HCCI3
- D. H3C+CI2 → H3CCI+Cİ
Explanation: Termination step in free radical substitution mechanism involvesi) Attack of free radical on other free radicalii) Bond formationiii)…
Correct answer: CI2CH+Ci → HCCI3- A. P4O10
- B. HNO3
- C. H2SO4
- D. H3PO4
Explanation: Dehydration of alcohols need dehydrating agents like concentrated H2SO4 P2O3 or P4O10.
Correct answer: HNO3- A. CH3CH=CH2 + HCI →
- B. CH3CH2CH=CH2+ HI→
- C. CH3CH=CH2 + HBr→
- D. CH3CH=CHCH3 + HBr→
Explanation: Markownikove's rule is obeyed by unsymmetrical alkenes Symmetrical alkanes like CH3CH-CHCH3 having no binding to obey the rule because…
Correct answer: CH3CH=CHCH3 + HBr→- A. CI+
- B. CI-1
- C. H+
- D. H∘
Explanation: In case of alkenes, the addition is started by the attack of electrophale.
Correct answer: H+- A. -119.5kJ/mole
- B. -358.5kJ/mole
- C. +150.5kJ/mole
- D. -208kJ/mole
Explanation: Resonance energy of benzene is +150.5 kJmol-1
Correct answer: +150.5kJ/mole11297. What is required other than anhydrous AICI3 when toluene is prepared by Friedal craft reaction?
- A. C6H6
- B. C6H6+ CH3CI
- C. C6H5C2H5
- D. C6H5CI and CH3CI
Explanation: In Friedal Craft's reaction AlCl3 is a catalyst. It accelerates the reaction between C6H6 an R-X like CH3CI.
Correct answer: C6H6+ CH3CI- A. Baeyar's test
- B. Br2(CCl4)
- C. Cl2(CCI4)
- D. Tollen's test
Explanation: Tollen's reagent shows no reaction with both alkenes and alkanes. It is used to differentiate in between an aldehyde and ketone.
Correct answer: Tollen's test11299. Alkanes are used as fuels. We burn them for many reasons. Which of the following is not its use?
- A. They are used to generate electricity in power stations
- B. They are used to heat our homes and cook our food
- C. They are used to provide electricity for electrolytic cell
- D. They are used to provide electricity for galvanic cell
Explanation: Explanation for this question will be added soon.
Correct answer: They are used to provide electricity for galvanic cell- A. It has a low boiling point
- B. Its enthalpy change formation (∆Ht) is positive
- C. It is susceptible to attack by nucleophilic reagent
- D. It tends to undergo electrophilic substitution rather addition reaction
Explanation: Explanation for this question will be added soon.
Correct answer: It tends to undergo electrophilic substitution rather addition reaction