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

Cyanogen bromide catalyses the hydrolysis of only those peptide bonds in which

  1. the carbonyl group is contributed by Lys or Arg residue

  2. the carbonyl group is contributed by Phe, Trp or Tyr residue

  3. the carbonyl group is contributed by Met residue

  4. the amino group is contributed by Phe, Trp or Tyr residue

  5. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cyanogen bromide catalyses the hydrolysis of only those peptide bonds in which the carbonyl group is contributed by Met residue.

Multiple choice

The reaction of Lucas reagent is fast with

  1. (CH3)3COH

  2. (CH3)2CHOH

  3. CH3CH2CH2OH

  4. CH3CH2OH

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lucas reagent (HCl/ZnCl2) reacts fastest with tertiary alcohols like (CH3)3COH (tert-butanol). Secondary alcohols react moderately, and primary alcohols react very slowly or not at all.

Multiple choice

Primary amine acts as

  1. electrophile

  2. Lewis base

  3. Lewis acid

  4. free radical

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Primary amines have a lone pair of electrons on the nitrogen atom, which they can donate to electron-deficient species (Lewis acids). This makes them Lewis bases. R-NH2 acts as a nucleophile in most reactions and can coordinate to metal ions or accept protons.

Multiple choice

Electrophile used in the nitration of Benzene is

  1. hydronium ion.

  2. sulphonic acid.

  3. nitronium ion.

  4. bromide ion.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nitration of benzene requires the nitronium ion (NO2+) as the electrophile. This species is generated in situ by the reaction of concentrated nitric acid with concentrated sulfuric acid, which acts as a dehydrating agent. The nitronium ion attacks the electron-rich benzene ring in an electrophilic aromatic substitution reaction.

Multiple choice

Which of the following compounds is used as a reagent in the Gabriel synthesis of amines?

  1. Potassium cyanide

  2. Potassium chloride

  3. Potassium cobaltinitrite

  4. Potassium dithionite
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Potassium phthalimide is a chemical compound of formula C8H4KNO2. If desired, it may be prepared by adding a hot solution of phthalimide to a solution of potassium hydroxide. This compound is a reagent used in the Gabriel synthesis of amines.

Multiple choice

Al4C3 reacts with water to form

  1. Al(OH)3+C2H6

  2. Al2O3+C2H6

  3. Al(OH)3+CH4

  4. Al2O3+CH4

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

 Al4C3  reacts with H2O to form aluminum hydroxide and methane.

Multiple choice

Carbowax is prepared by which of the following methods?

  1. When para-nitroso N-N dimethylaniline is decomposed by caustic soda.

  2. When dimethylene amine hydrochloride reacts with NaOH.

  3. When thermal decomposition of hexamethyl ammonium hydroxide takes place.

  4. When dimethyl amine reacts with nitrous acid.

  5. When the ethylene oxide is polymerised.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This option is correct because when ethylene oxide are polymerised it gives polyethyleneglycol, which is known as carbowax.

Multiple choice

What is Skraup synthesis known for?

  1. Synthesis of quinoline

  2. Synthesis of quinaldine

  3. Synthesis of isoquinoline

  4. Synthesis of indole

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

This option is correct.