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

Estimation of halogens in organic compound is done by:

  1. Duma' s method

  2. Messenger' s method

  3. Carrius method

  4. kjeldahls' method
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Carius method is a quantitative analytical technique used to determine the amount of halogens, phosphorus, or sulfur in organic compounds. Dumas and Kjeldahl methods are specifically used for the estimation of nitrogen.

Multiple choice

Directions: In the question given below, there are two statements labeled as Assertion (A) and Reason (R). Mark your answer as per the codes provided below: Assertion: Chlorination of ethylbenzene with Cl2 in presence of heat and light mainly yields 1-chloro-2-phenylethane. Reason: The reaction occurs through intermediate formation of the radical, C6H5CH2C*H2.

  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
E Correct answer
Explanation

This option is correct because chlorination of ethylbenzene with Cl2 in presence of heat and light gives 1-chloro-1-phenylethane, and the reaction occurs through intermediate formation of the benzylic radical, C6H5C.HCH3.

Multiple choice

Which of the following statements is not correct?

  1. When ethyne reacts with chlorido(methyl)magnesium, hydrogen is evolved.
  2. OCOCH3 is an ortho-, para- directing group but –COOCH3 is a meta-directing group.
  3. Lindlar catalyst is a heterogeneous catalyst that consists of palladium deposited on calcium carbonate or barium sulfate and treated with various forms of lead.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 2 and 3

  5. 1 and 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is wrong because Lindlar catalyst is a heterogeneous catalyst that consists of palladium deposited on calcium carbonate or barium sulfate and treated with various forms of lead, is true statement.

Multiple choice

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

Directions: In each of the questions given below, there are two statements labeled as Assertion (A) and Reason (R). Mark your answer as per the codes provided below:

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not the correct explanation of A.
C. A is true but R is false.
D. A is false but R is true.
E. Both A and R are false.

  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

In aniline, the –NH2 group: A. activates the benzene ring via both inductive and resonance effect. B. activates the benzene ring via resonance effect and deactivates it via inductive effect. C. activates benzene ring via inductive effect and deactivates it via resonance effect.

  1. Only A

  2. Only B

  3. Only C

  4. Only A and B

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

This option is correct because in aniline, –NH2 group activates the benzene ring via resonance effect and deactivates it via inductive effect.

Multiple choice

Which of the following compounds will undergo Cannizzaro reaction? P. (CH3)3C-CHO Q. C6H5CHO R. C6H5CH2CHO S. CH3CH2CHO

  1. Only P and Q

  2. Only P and R

  3. Only Q and R

  4. Only Q and S

  5. Only R and S
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aldehydes having no alpha hydrogen, when heated with conc. alkali, undergo self-oxidation-reduction to yield a mixture of corresponding alcohol and carboxylate salt. This reaction is known as Cannizzaro reaction. Since (CH3)3C-CHO and C6H5CHO do not have alpha hydrogen, they will undergo Cannizzaro reaction.

Multiple choice

Aniline is prepared by

  1. Zinin's reaction

  2. Pfitizinger's reaction

  3. Gould-Jacobs' reaction

  4. Doebner-Miller's reaction

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

This option is correct. Nitro aromatic compounds are converted to amines by the action of sodium sulphides.