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

The sum total of all reactions occurring in the body, whether constructive or destructive is known as

  1. catabolism

  2. metabolism

  3. anabolism

  4. physiology
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Metabolism is the sum of all chemical reactions in an organism, including both anabolic (constructive, building complex molecules) and catabolic (destructive, breaking down molecules) pathways. Catabolism only refers to breakdown reactions, while anabolism refers only to building reactions. Physiology is the broader study of how organisms function.

Multiple choice

Which of the following expressions represents the equilibrium constant for the following redox reaction?

Cu2+(aq) + Zn(s) -------> Zn2+(aq) + Cu(s)

  1. [Zn2+][Cu]/[Cu2+][Zn]

  2. [Cu2+][Zn]/[Zn2+][Cu]

  3. [Cu2+]/[Zn2+]

  4. [Zn2+]/[Cu2+]
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because while the formula for equilibrium constant it is generalized as K = [products]/[reactants] ………………..where the concentration of pure reactants and products is taken to be unity.In the given reaction the concentration of reactant Zn(s) and product Cu(s) is to be taken unity and hence we will get the correct answer as K = [Zn2+]/[Cu2+]

Multiple choice

For the reaction given below, identify the type of graph obtained between [Ba2+] and [SO42-].

BaSO4(s) <------> Ba2+(aq) + SO42-(aq)

  1. Straight line graph, ( y = mx + c ) type

  2. Rectangular Hyperbola

  3. Constant graph ( y = 0) type

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct and can be explained as follows: For the give n reaction the equilibrium constant is given byK = [Ba2+][SO42-]……………………….or we can say that [Ba2+] and [SO42-] are having inversely proportional relationship whose graph is given by a rectangular hyperbola.

Multiple choice

Which of the following reactions proceed(s) via free radical intermediates?

  1. Hundsdiecker reaction
  2. Sandmeyer reaction
  3. Dieckmann condensation reaction
  4. Claisen condensation reaction

  1. Only 1

  2. Only 2

  3. 1 and 2

  4. 2 and 3

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hundsdiecker reaction and Sandmeyer reaction both proceed via free radical formation as an intermediate. Both Dieckmann condensation reaction and Claisen condensation reaction proceed via the formation of carbanions as an intermediate. Hence, 1 and 2 both the reactions proceed via free radical formation as an intermediate.

Multiple choice

Which of the following pairs of ‘reaction: corresponding reagent’ is incorrectly matched?

  1. Etard reaction: PPh3/CX4

  2. Duff reaction: (CH2)6N4/Glacial acetic acid/H3O+

  3. Boebner-Miller synthesis: HCHO/H2SO4

  4. Clemmensen reduction: Zn-Hg/HCl

  5. Cannizzaro reaction: KOH
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The oxidation of aromatic methyl groups to aldehydes with cromyl chloride (CrO2Cl2) is known as Etard reaction. The reaction of triphenylphosphine and tetrahalomethanes (CCl4, CBr4) with alcohols is a ready method to convert an alcohol to the corresponding alkyl halide under mild conditions in high yields. This reaction is known as Appel reaction.

Multiple choice

Which of the following reactions involve the formation of carbocation as reactive intermediate?

  1. Friedal craft reaction
  2. Baeyer-Villiger oxidation
  3. Curtius rearrangement
  4. Wagner-Meerwein rearrangement

  1. 1 and 2

  2. 1 and 3

  3. 2 and 4

  4. 1, 2 and 3

  5. 1, 2 and 4
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

In the heterolytic fission of a C-X bond in an organic molecule, if X is more electronegative than carbon atom, the former takes away the bonding electron pair and becomes negatively charged and results in the formation of positively charged species which is called carbocation. Many reactions are involved in the formation of carbocation as reactive intermediate like Friedal craft reaction, Baeyer-Villiger oxidation, Wagner-Meerwein rearrangement etc. Curtius rearrangement involves in the formation of nitrene with two unshared pair of electrons as a reactive intermediate.

Multiple choice

Which of the following reactions are involved in the formation of carbenes as reaction intermediates?

  1. Carbylamines reaction
  2. Reimer-Tiemann reaction
  3. Wolff rearrangement
  4. Lossen rearrangement

  1. 1 and 2

  2. 2 and 3

  3. 3 and 4

  4. 1, 2 and 3

  5. 2, 3 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A reaction intermediate is a molecular entity that is formed from the reactants and reagents to give products of a chemical reaction. Carbenes are highly reactive species having a very short life time (<1 sec) with two unshared electrons. The reactions involved in the formation of carbenes are Carbylamines reaction, Reimer-Tiemann reaction, Wolff rearrangement etc. In Lossen rearrangement, the reactive intermediate is a nitrene with two unshared pair of electrons.

Multiple choice

Directions: In the question given below, there are two statements labelled Assertion (A) and Reason (R). Choose the correct option.

Assertion: The compound C6H5CH=CHCl is called β-chlorostyrene. Reason: In organic halides, the carbon atom is attached to the halogen atom designated as α.

  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 styrene, carbon atom attached to phenyl group is designated as α-carbon, while that carrying Cl-atom is designated as β-carbon.

Multiple choice

8 g of sulphur is burnt to form SO2, which is oxidised by Cl2 water. The solution is then treated with BaCl2 solution. The amount of BaSO4 precipitated would be

  1. 1 mole

  2. 2 mole

  3. 3 mole

  4. 0.75 mole

  5. 0.25 mole
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The required reaction is S + O2→ SO2 + Cl2 (water) → SO42– + BaCl2→BaSO4 +2Cl–. Moles of sulphur = (8 / 32) = (1 / 4),  moles of SO2. Therefore, moles of BaSO4 precipitated = 0.25. (applying principle of atom conservation). Hence, this is a correct option.

Multiple choice

The catalyst (s) used in the conversion of ethene to ethanal in Wacker process is/are

A. PdCl2 B. CuCl2 C. Fe D. TiCl4/(C2H5)3Al

  1. A only

  2. C only

  3. A and B

  4. B and C

  5. C and D
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

PdCl2 is used as a ctatlyst in the conversion of ethene to ethanal in Wacker process. In Deacon process, CuCl2 is used as a catalyst for the preparation of chlorine from HCl. Fe is used as a catalyst in Haber process for the formation of ammonia. A mixture of TiCl4 and triethyl aluminium (Zeigler-Natta catalyst) is used for converting SO2 to SO3 in Contact process.