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JEE Advanced

Explore popular questions from Redox Reactions for JEE Advanced. This collection covers Redox Reactions previous year JEE Advanced questions hand picked by experienced teachers.

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Redox Reactions

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Q 1. A metal ion {tex} \mathrm M^ { 3 + } {/tex} loses three electrons; its oxidation number will be

A

{tex} + 3 {/tex}

{tex} + 6 {/tex}

C

{tex}0{/tex}

D

{tex} - 3 {/tex}

Explanation

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Q 2. {tex} a \mathrm { K } _ { 2 } \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } +b \mathrm { KCl } + c\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } \rightarrow x \mathrm { CrO } _ { 2 } \mathrm { Cl } _ { 2 } + y \mathrm { KHSO } _ { 4 } + \mathrm { zH } _ { 2 } \mathrm { O } {/tex}
The above equation balanced when

A

{tex} a = 2 , b = 4 , c = 6 {/tex} and {tex} x = 2 , y = 6 , z = 3 {/tex}

B

{tex} a = 4 , b = 2 , c = 6 {/tex} and {tex} x = 6 , y = 2 , z = 3 {/tex}

C

{tex} a = 6 , b = 4 , c = 2 {/tex} and {tex} x = 6 , y = 3 , z = 2 {/tex}

{tex} a = 1 , b = 4 , c = 6 {/tex} and {tex} x = 2 , y = 6 , z = 3 {/tex}

Explanation

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Q 3.

The reagent with which both acetaldehyde and acetone react easily is:

A

Tollens reagent

B

Schiffs regent

Grignard reagent

D

Fehling’s solution

Explanation

Acetaldehyde reacts with Tollens, Schiff''s, and Fehling''s solution but acetone does not. But with Grignard reagent both react

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Q 4.

The compound (C) is:

B

C

D

Explanation

The -keto acid on heating undergoes decarboxy lation easily

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Q 5.

A metal ion loses three electrons; its oxidation number will be

A

3

6

C

0

D

Explanation

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Q 6.

The Product (A) is:

A

B

D

Explanation

The reduction of group under basic condition with (Zn dust ) gives hydrazobenzene compound. So the answer is (c)

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Q 7.

The above equation balanced when

A

and

B

and

C

and

and

Explanation

The balanced equation is

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Q 8.

The product (A)and (B) are:

B

C

D

None

Explanation

Lemieux reagent oxidises RCH to RCOOH and . So the answer is (a)

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Q 9.

Which of the following is a redox reaction?

A

B

C

Explanation

In (a),(b) and (c), oxidation number does not change

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Q 10.

When copper is treated with a certain concentration of nitric acid, nitric oxide and nitrogen dioxide are liberated in equal volumes according to the equation

The coefficients and are

A

2 and 3

2 and 6

C

1 and 3

D

3 and 8

Explanation

The balanced equation is

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Q 11.

For the redox reaction

the coefficients , and are

2,5,16

B

16,5,2

C

5,16,2

D

2,16,5

Explanation

Balanced equation is

and are 2,5,16

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Q 12.

The number of moles of requried to oxidize 1 mol of Fe in acidic medium is

0.6

B

1.67

C

0.2

D

0.4

Explanation

Equivalent of Equivalent of

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Q 13.

The difference in the oxidation numbers of the two types of sulphur atoms in is

A

4

5

C

6

D

7

Explanation

is salt of which has the following structure



Difference in oxidation number of two types of sulphur = 5

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Q 14.

The oxidation state of S in is

A

2

B

4

6

D

7

Explanation

: It is peroxodisulphuric acid. So oxidation state of

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Q 15.

The oxidation state of Fe in is

A

3/2

B

4/5

C

5/4

16/3

Explanation

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Q 16.

In the balanced chemical reaction

, and , respectively, correspond to

5,6,3,3

B

5,3,6,3

C

3,5,3,6

D

5,6,5,5

Explanation

The balanced equation is

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Q 17.

Which of the following is not a disproportionation reaction?

A

B

C

Explanation

Disproportionation involves simultaneous oxidation and reduction of the same atom in a molecule

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Q 18.

Fehling’s solution can make distinction between:

and

B

C

D

and HCHO

Explanation

a.Fehling''''''''s solution reacts only with aliphatic aldehyde, not with aromatic aldehyde

b.F.S. reacts with and also with -hydroxy ketones

c.F.S. reacts with both HCHO and with -hydroxy ketones

d.F.S. reacts with both aliphatic aldehydes ( and HCHO). So the answer is (a)

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Q 19.

The reagent (A) is:

A

LAH

B

HI+P

C

Explanation

a. LAH reduces both ester and acid to alcohols

b. HI + P reduces both ester and acid to alkane

c. reduces only ester to aldehyde and alcohol

d. selectively reduces acid to alcohol (although it can also reduce ester to alcohols) but acid group is reduced in the presence of esters

So the answer is (d)

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Q 20.

Which acetaldehyde is heated with Fehling’s solution, it gives a precipitate of:

A

Cu

B

D

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Q 21.

In which of the following is the highest oxidation state not possible?

A

C

D

Explanation

Xe shows +8 oxidation state in but it does not exist because of steric hindrance of 8 F atoms

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Q 22.

The oxidation state of nitrogen is correctly given for


Compound

A

[CO 0

B

-2

C

+2

Explanation

a.

oxidation state of N=

b.

Oxidation state of N=

c.

Oxidation number of N=

d.

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Q 23.

Which of the following statements is not correct about the reaction given below?

A

Fe is oxidized from to

B

Carbon is oxidised from to

C

N is oxidized from

Carbon is not oxidized

Explanation

In oxidation of C is +2, and it changes to +4 oxidation state in . So is also oxidised

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Q 24.

The oxidation number of P in is

A

3

B

2

5

D

Explanation

Oxidation number of

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Q 25.

The compound (A) is:

A

Aq.

B

/

D

Explanation

In (a), aqueous (cold) will hydroxylate the ( ) bond

In (b), (iodoform reaction) will not react since there is no ( ) or or ( ) group

In (c), Tollens reagent will convert the group to ( ) group without affecting ( ) bond

In (d), will not react, since it does not contain allylic or benzylic alcoholic group. So the answer is (c)