Test: Diazonium Salts


20 Questions MCQ Test Chemistry Class 12 | Test: Diazonium Salts


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QUESTION: 1

Benzene diazonium chloride when reacts with hypophosphorus acid produces

Solution:

QUESTION: 2

p-amino azo benzene is obtained by treating diazoniumchloride with:

Solution:

p-amino azo benzene is obtained by treating diazonium chloride with aniline. The reactions are specifically acid catalyzed and involve pre‐equilibrium formation of amine and diazonium salt followed by rate‐limiting attack of the diazonium ion at a C‐atom (C‐coupling) to give the corresponding amino azo compounds.

QUESTION: 3

When hypophosphorous acid is treated with diazonium salts, it is reduced to:

Solution:

The correct answer is option A

Hypophosphorous acid when treated with diazonium salts is reduced to arenes.
ArN2Cl + H3PO2 + H2O ⟶ ArH + N2 + H3PO3 +HCl

QUESTION: 4

 Which of the following amine will form stable diazonium salt at 273-283 K ?

Solution:

The correct answer is Option A.
Aromatic Primary amine will form the most stable diazonium salt because it releases water when it reacts with nitronium ions. If aliphatic primary amine reacts with nitrosonium ion it Also releases water but in this case water reacts with alkyl diazonium salt and it forms alcohol while benzene diazonium salt does not react with water at this temperature.

QUESTION: 5

Replacement of diazo group by other groups is helpful in preparing those substituted aromatic compounds which cannot be prepared by

Solution:

Replacement of diazo group by other group is helpful in preparing compounds which are not/ cannot be produced by direct nucleophilic substitution reaction.This is because,to substitute in aromatic ring, the nucleophilic should leave the partial double bond, which is more energy required than in haloalkane.

QUESTION: 6

ArN+ Cl   ArX + N2 is called as:

Solution:

This reaction is called Gattermann reaction. In this reaction, Cl, Br and CN can be introduced into the benzene ring by simply treating diazonium salts with HCl, HBr, KCN. Respectively in presnce of copper powder instead of using Cu(I) salts.

QUESTION: 7

Which of the following amine gives diazonium salt on reaction with HNO2?

Solution:

C6H5NH2 reacts with HNO2 to forms diazonium salts, the reaction are as follows,
C6H5NH2 + HNO2 ------> C6H5OH + H2O + N2

QUESTION: 8

On heating an aliphatic primary amine with chloroform and ethanolic potassium hydroxide, the organic compound formed is 

Solution:
QUESTION: 9

 What happens when benzene diazonium chloride is treated with potassium cyanide in presence of Cu powder?

Solution:

The correct answer is option D
By treating diazonium salts with cuprous cyanide or KCN and copper powder it forms aryl nitrile. Illustrative is the preparation of benzonitrile using the reagent cuprous cyanide:

QUESTION: 10

 When ethanol is treated with benzene diazoniumchloride it forms:

Solution:

The correct answer is option A
When C2H5OH (ethanol) is treated with C6H5N2Cl it forms benzene.
Some mild reducing agents like C2H5OH themselves get oxidized to ethanol after reducing C6H5N2Cl to benzene.

QUESTION: 11

The conversion of primary aromatic amines into diazonium salts is known as:

Solution:

The process of conversion of primary aromatic amines into its diazonium salt is called diazotization. Diazonium salts are important synthetic intermediates that can undergo coupling reactions to form azo dyes and electrophilic substitution reactions to introduce functional groups.

QUESTION: 12

By treating diazonium salts with cuprous cyanide or KCN and copper powder it forms:

Solution:

The correct answer is option C
By treating diazonium salts with cuprous cyanide or KCN and copper powder it forms aryl nitrile.
CuCN/KCN
ArN2+ Cl–—————> ArCN + N2

QUESTION: 13

Benzene diazonium chloride forms orange red dye with:

Solution:

Benzene diazonium chloride forms orange red dye with resorcinol, Reaction of benzene diazonium chloride with resocinol in basic medium is a coupling reaction,in which p-hydroxyazobenzene is obtained .Which is nothing but orange dye.

QUESTION: 14

The stability of benzene diazonium salts is because of

Solution:

None of the errors that are pointed are correct.

Their stability is because of resonance. D is the correct answer.

 

What is the resonance structure of aromatic diazonium salt? - Quora

QUESTION: 15

 Azo-dye test is given by:

Solution:

This test is given by aromatic primary amines. Aromatic primary amines react with nitrous acid to form diazonium salts. These diazonium salts undergo coupling reaction with β-naphthol to form orange coloured azo dye.

QUESTION: 16

The general formula of Diazonium salt is:

Solution:

The correct answer is option A
The diazonium salts or diazonium compounds are the class of organic compounds with general formula R−N2+X. Here, X is an organic or inorganic anion (for example, Cl–, Br, BF4, etc.) and R is an alkyl or aryl group. The term is derived from two words. ‘Di 'refers to ‘two’, azo is indicative of ‘nitrogen’ and ium implies that it is cationic in nature.

QUESTION: 17

When diazonium salt solution is treated with KI, it forms:

Solution:

When diazonium salt solution is treated with KI it introduces −I group in benzene ring to form Iodobenzene as a major product.

QUESTION: 18

 Diazo coupling is useful to prepare:

Solution:

The correct answer is option C            
Azo dyes are derived by coupling of a phenol adsorbed on the surface of a fabric with a diazonium salt. Dyes can be prepared by diazo coupling.

QUESTION: 19

Benzene diazonium chloride on reaction with phenol in weakly basic medium gives:

Solution:

The correct answer is Option A.
Benzene diazonium chloride in reaction with phenol in a basic medium gives p-Hydroxy azobenzene. This is an example of the coupling reaction.

QUESTION: 20

When diazonium salt solution is treated with water at a temperature of 283 K it forms?

Solution:

Benzene diazonium chloride is hydrolysed to phenol when heated with water.
ArN2Cl + H2O ----> ArOH + N2 + HCl 

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