All Free Chemistry MCQs with Answers

• A. Fast decomposition of organic matter
• B. Decomposition of plants
• C. Decomposition of animals
• D. Biochemical decomposition of dead organic matter

Explanation: Fossil energy sources, including oil, coal and natural gas, are non-renewable resources that formed when prehistoric plants and animals…

• A. At the start of procedure
• B. Somewhere in the middle of balancing
• C. After adding two half reactions
• D. Before adding two half reactions

Explanation: A redox equation can be balanced using the following stepwise procedure: (1) Divide the equation into two half-reactions.

• A. Acidic Medium
• B. Basic Medium
• C. Neutral solution
• D. All of these

Explanation: The addition of OH⁻ ions can happen in all three scenarios - acidic, basic, and neutral solutions.

• A. Baeyer reagent
• B. Lucas Test
• C. Decolorization of Br2 in CCl4
• D. Orange red colour with CH4/AlCl3

Explanation: Option D is correct.When aromatic hydrocarbons are treated with chloroform and aluminum chloride, orange to red colours are obtained.

• A. Meta directing and deactivating group
• B. Ortho-para directing and deactivating group
• C. Ortho-para directing and activating group
• D. Ortho directing and activating only
• E. Para directing and deactivating only

Explanation: The explanation for this question will be added soon.

• A. Cyclohexane
• B. Hexane
• C. Phenol
• D. Benzoic Acid
• E. Hexene

Explanation: The explanation for this question will be added soon.

• A. 2
• B. 3
• C. 6
• D. 4

Explanation: Option A is correct since benzene is a resonance hybrid of these two structures shown in the image: Option B is incorrect since it states…

• A. Aliphatic
• B. Aromatic
• C. Alicyclic
• D. None of these

Explanation: Aromatic compounds burn with sooty flame because they have a ring structure of carbon atoms.

• A. Naphthalene
• B. Phenanthrene
• C. Anthracene
• D. Triphenylmethane

Explanation: The structure of Triphenylmethane is as follows:

• A. Dil HCL
• B. Ethyl alcohol
• C. Acetic acid
• D. Acetyl chloride

Explanation: In aniline, the amino group is an electron-releasing group. It activates the benzene ring towards an electrophilic aromatic substitution…

• A. AlCl3 / Cl2 ; H2 / Rh / C
• B. Cl2 / UV light ; H2 / Rh / C
• C. H2 / Rh / C ; AlCl3 / Cl2
• D. HCl ; H2 / Rh / C

Explanation: A would be the answer as we have electrophilic substitution taking place involving the formation of a Cl+ ion which is formed via the…

• A. AlCl3
• B. NaOH
• C. Chlorobenzenes
• D. Cumene

Explanation: Sodium benzoate is converted to benzene by heating with a mixture of NaOH and CaO.

• A. Alkylation
• B. Halogenation
• C. Nitration
• D. Acylation

Explanation: Acetophenone is formed by friedal craft acylation. This reaction involves acylation of benzene with acyl chloride or acyl anhydride

• A. HSO4-
• B. H2SO4
• C. SO3
• D. HSO3

Explanation: SO3 acts as an electrophile in sulphonation. Sometimes H2SO4 is also seen in equations in place of SO3 because H2SO4 dissociates to give…

• A. Good electrophile
• B. Good nucleophile
• C. Resonance hybrid
• D. Extraordinary stable

Explanation: Benzene is a nucleophile because of its delocalized electrons thus the molecule has electron-rich areas which are frequently attacked by…

• A. In alkynes to identify the position of triple bond
• B. In arenes to identify the position first substitution
• C. In arenes to identify the position second substituition
• D. In all hydrocarbons to identify the position of functional group

Explanation: Ortho, para, and meta are prefixes used to designate the relative positions of second substituent groups on an aromatic ring in organic…

• A. Numerically
• B. Alphabetically
• C. Alphanumerically
• D. None of these options is correct

Explanation: The substituents in arenes are put in alphabetical order when they are different.

• A. Low melting and low boiling points
• B. High melting and high boiling points
• C. Low melting and high boiling points
• D. High solubility in polar solvents

Explanation: OPTION A: Arenes are compounds that contain benzene ring(s). Since the only possible intermolecular force of attraction, in this case, are…

• A. Elimination
• B. Addition
• C. Substitution
• D. Hydrogenation

Explanation: Option A: There is no such evidence of elimination reaction in Benzene since it completely destroys the stability of Benzene.Addition…

• A. Hydrogenation
• B. Dehydrogenation
• C. Dehydration
• D. None of these options are correct

Explanation: Dehydrogenation is the process by which hydrogen is removed from an organic compound to form a new chemical (e.g., to convert saturated…