Chemistry

Chemical Reactions and Equations

684 Questions

Chemical reactions and equations form a foundational chemistry topic where students identify reaction products, balance chemical formulas, and classify reaction types. It covers critical mechanisms like Markovnikov's rule, precipitation, and endothermic or exothermic processes. These questions are highly common in general science sections of state and central government competitive exams.

Endothermic reactionsPrecipitation reactionsDehydrohalogenation of alkyl halidesChemical equation balancingReaction product identification

Chemical Reactions and Equations Questions

Multiple choice

Which of the following statements is/are incorrect? A. In two step reaction, the rate determining step has the lowest energy of activation. B. All the carbon atoms in bicyclobutane are sp3-hybridized. C. Free radicals are produced by homolytic cleavage of covalent bonds.

  1. Only A

  2. Only B

  3. Only C

  4. A, B and C

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct,  because in two step reaction, the rate determining step has the highest energy of activation.

Multiple choice

Which of the following methods is used to get nitrosobenzene?

  1. Aniline is oxidised in presence of hydrogen peroxide.

  2. Aniline is oxidised in presence of the potassium permagnate and sulphuric acid.

  3. Aniline is oxidised in presence of potassium dichromate and sulphuric acid.

  4. Para-nitroacetanilide is hydrolysed.

  5. Options 2 and 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because when aniline is oxidised in the presence of hydrogen peroxide, we get nitrosobezene.

Multiple choice

Which of the following statements is/are true? A. Benzene reacts with isobutyl chloride in presence of anhydrous AlCl3 to give isobutyl benzene. B. Bayer’s reagent can be used to distinguish cyclopropane from propene. C. Ethyne and its derivatives give white precipitate with ammoniacal silver nitrate solution.

  1. Only A

  2. Only B

  3. Only C

  4. Both A and B

  5. Both B and C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct, because propene decolourises Bayer’s reagent but cyclopropane being saturated does not.

Multiple choice

Assertion: Reaction of 1, 3-dibromopropane with zinc produces cyclopropane. Reason: The reaction of alkyl halides with zinc dust is called Frankland reaction.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct, because the two carbon atoms carrying the Br-atoms in 1, 3-dibrobopropane are close, and hence undergo intermolecular cyclisation to give cyclopropane.

Multiple choice

Assertion: Fredel-Crafts reaction of benzene with n-propyl chloride gives isopropylbenzene. Reason: Benzene undergoes electrophilic substitution readily.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because the initially formed n-propyl cation first undergoes rearrangement by 1, 2-hydride shift to more stable isopropyl cation, which then attacks the benzene ring to form isopropylbenzene.

Multiple choice

Assertion: Benzene reacts with Cl2 in presence of light to form BHC. Reason: BHC is also called gammexane or 666.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because in presence of light, free radical addition of Cl2 occurs to the three double bonds giving BHC.

Multiple choice

Assertion: Addition of HI to vinyl chloride produces 1-chloro-1-iodoethene. Reason: HI adds to vinyl chloride against Markownikov’s rule.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct, because HI adds to vinyl chloride according to Markownikov’s rules.

Multiple choice

Assertion: Addition of Br2 to maleic acid gives (+) and (-) forms of the product. Reason: Addition of Br2 to maleic acid follows trans-addition.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because both assertion and reason are true and reason, 'addition of Br2 to maleic acid follows trans-addition' is the correct explanation of assertion.

Multiple choice

Assertion: Both cyclopropane and propene give addition reactions readily. Reason: Cyclopropane and propene are isomers of each other.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because propene being unsaturated undergoes addition reactions. In contrast, cyclopropane being strained readily undergoes ring cleavage to yield addition products.

Multiple choice

Assertion: Propene reacts with perbenzoic acid to produce 1, 2-epoxypropane. Reason: In this reaction, propene acts as a nucleophile.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is NOT the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct, because propene acts as a nucleophile and reacts with perbenzoic acid to produce 1, 2-epoxypropane.

Multiple choice

Which of the following statements is/are false?

  1. Lindlar’s catalyst is palladium supported over calcium carbonate, but partially poisoned by addition of lead acetate.

  2. –COOCH3 is a meta-directing group while OCOCH3 is an ortho-, para- directing group.

  3. Both 1 and 2

  4. When acetylene reacts with methyl magnesium bromide, hydrogen is evolved.

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because when acetylene reacts with methyl magnesium bromide, CH4 is produced. HC≡CH + CH3MgBr → HC≡CMgBr + CH4