All Free Chemistry MCQs with Answers

• A. The rupturing of the benzene ring
• B. Substitution reaction
• C. Addition reaction
• D. No reaction

Explanation: Reacting bromine with benzene in the presence of sunlight will result in bromination through a substitution reaction.

• A. NO3 NO
• B. NO
• C. NO2- NO2
• D. NO2

Explanation: The nitronium ion (NO2+) is represented as NO2, where nitrogen is bonded to two oxygen atoms with a positive charge.

• A. alkene
• B. alkyl
• C. aldehyde
• D. saturated hydrocarbon

Explanation: When one hydrogen atom is removed from an alkane, the resulting fragment is called an alkyl group.

• A. CaO and KOH
• B. decarboxylation
• C. NaOH and Na₂O
• D. Na2O and KOH

Explanation: Soda lime is a mixture of calcium oxide (CaO) and sodium hydroxide (NaOH).

• A. Grignard reagent
• B. Metallic alkyl halide
• C. Both a & b
• D. Alkyl halide

Explanation: R-Mg-Br is called a Grignard reagent, named after the French chemist François Auguste Victor Grignard who discovered these compounds.

• A. CO2 and H2O
• B. ethyne
• C. CH3OH
• D. CO + H2O + C

Explanation: Ethyne (acetylene) is the most reactive among the given options. It is highly reactive due to its triple bond, which can easily undergo…

• A. CnH2n+2
• B. CnH2n-2
• C. CnH2n
• D. CnH2n+1

Explanation: The general formula of an alkyne is CnH2n-2.

• A. dihalo alkane
• B. alkane
• C. alkynes
• D. both b & c

Explanation: Reactivity due to pi-electrons is present in both alkenes (b) and alkynes (c).

• A. hydrogen bonding
• B. irregular shape of the molecules
• C. irregular shape of the molecules and strong intermolecular forces
• D. greater molecular size

Explanation: The greater viscosity of honey is primarily attributed to the presence of hydrogen bonding between the molecules in honey, specifically…

• A. Chloroform
• B. Acetylene
• C. Di-vinyl acetylene
• D. Chloroprene

Explanation: Synthetic rubber is made by the polymerization of chloroprene (2-chloro-1,3-butadiene).

• A. -119.5 kJ/mol
• B. -358.5 kJ/mol
• C. +150.5 kJ/mol
• D. -208 kJ/mol

Explanation: Resonance energy is the difference between the actual enthalpy of hydrogenation of benzene (-208 kJ/mol) and the theoretical enthalpy…

• A. One of the products exists as three stereoisomers
• B. Two pairs of diastereomers are obtained only
• C. Only one meso stereoisomer is obtained
• D. Two pairs of enantiomers are obtained

Explanation: The correct answer is Option D: Two pairs of enantiomers are obtained because enantiomers come in pairs and a single compound cannot form…

• A. Bromine water test
• B. Hydroxylation
• C. Ozonolysis
• D. Both "A" and "B"

Explanation: When differentiating between an alkane and an alkene, it is important to consider their saturation levels.

• A. They have high percentage of hydrogen
• B. They have a ring structure
• C. They have high percentage of carbon
• D. They resist in reaction with air

Explanation: Aromatic compounds burn with a sooty flame because the benzene rings in their structure resist complete combustion, leading to the…

• A. Introduction of R-group in the benzene ring in the presence of AlCl3 is called alkylation
• B. Introduction of acyl group in the benzene ring in the presence of AlCl3 is called acylation
• C. Benzene cannot undergo polymerization
• D. Ozonolysis of benzene results in the formation of (COOH)2

Explanation: The correct answer is option D. Ozonolysis of benzene does not result in the formation of (COOH)2, but rather produces glyoxal as the…

• A. Saturated hydrocarbons
• B. Unsaturated hydrocarbon
• C. Both of above
• D. None ofthese

Explanation: Alkanes are indeed known as saturated hydrocarbons because they contain only single bonds between carbon atoms, meaning they have the…

• A. Peroxide effect
• B. Markovnikov's rule
• C. Anti markovnikov's rule
• D. Kharish effects

Explanation: Markovnikov's Rule dictates the addition of hydrogen bromide to an unsymmetrical alkene, where the hydrogen attaches to the carbon with…

• A. C6H6O9
• B. C6H5O8
• C. C6H6O6
• D. C6H6O7

Explanation: Benzenetriozonide is formed when benzene reacts with ozone, resulting in the molecular formula C6H6O9.

• A. Three
• B. Four
• C. Six
• D. Eight

Explanation: Benzene is a planar molecule with a hexagonal ring of carbon atoms and alternating double bonds.

• A. Benzaldehyde
• B. Glyoxal
• C. Glyoxime
• D. Glycol

Explanation: The hydrolysis of benzenetriazolide will yield three moles of glyoxal. The reaction is shown below:C6H5N3C6H5 + 6H2O ?