JEE Main > Redox Reactions

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


Q 1.    

Correct4

Incorrect-1

The number of moles of {tex} \mathrm { CaCl } _ { 2 } {/tex} needed to react with excess of {tex} \mathrm { AgNO } _ { 3 } {/tex} to produce 4.31{tex} \mathrm { g } {/tex} of AgCl.

A

0.03

0.015

C

0.045

D

0.06

Explanation

Q 2.    

Correct4

Incorrect-1

Calcium carbonate reacts with aqueous HCl to give {tex} \mathrm { CaCl } _ { 2 } {/tex} and {tex} \mathrm { CO } _ { 2 } {/tex} according to the reaction, {tex} \mathrm { CaCO } _ { 3 } ( \mathrm { s } ) + {/tex} {tex} 2 \mathrm { HCl } ( \mathrm { aq } ) \rightarrow \mathrm { CaCl } _ { 2 } ( \mathrm { aq } ) + \mathrm { CO } _ { 2 } ( \mathrm { g } ) + \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } ) {/tex} The mass of {tex} \mathrm { CaCO } _ { 3 } {/tex} is required to react completely with 25{tex} \mathrm { mL } {/tex} of 0.75{tex} \mathrm { M } \mathrm { HCl } {/tex} is

A

0.1{tex} g {/tex}

B

0.5{tex} g {/tex}

C

1.5{tex} g {/tex}

0.94{tex} g {/tex}

Explanation

Q 3.    

Correct4

Incorrect-1

If ten volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be

10

B

20

C

48

D

12

Explanation

Q 4.    

Correct4

Incorrect-1

1.60 g of a metal were dissolved in {tex}\mathrm {HNO}_ { 3 } {/tex} to prepare its nitrate. The nitrate on strong heating gives 2 g oxide. The equivalent weight of metal is

A

16

32

C

48

D

12

Explanation

Q 5.    

Correct4

Incorrect-1

How many moles of electron is needed for the reduction of each mole of {tex} \mathrm { Cr } {/tex} in the reaction,
{tex} \mathrm { CrO } _ { 5 } + \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } \longrightarrow \mathrm { Cr } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } + \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { O } _ { 2 } {/tex}

A

4

3

C

5

D

7

Explanation

Q 6.    

Correct4

Incorrect-1

The incorrect order of decreasing oxidation number of S in compounds is

A

{tex} \mathrm { H } _ { 2 } \mathrm { S } _ { 2 } \mathrm { O } _ { 7 } > \mathrm { Na } _ { 2 } \mathrm { S } _ { 4 } \mathrm { O } _ { 6 } > \mathrm { Na } _ { 2 } \mathrm { S } _ { 2 } \mathrm { O } _ { 3 } > \mathrm { S } _ { 8 } {/tex}

B

{tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 5 } > \mathrm { H } _ { 2 } \mathrm { SO } _ { 3 } > \mathrm { SCl } _ { 2 } > \mathrm { H } _ { 2 } \mathrm { S } {/tex}

C

{tex} \mathrm { SO } _ { 3 } > \mathrm { SO } _ { 2 } > \mathrm { H } _ { 2 } \mathrm { S } > \mathrm { S } _ { 8 } {/tex}

{tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } > \mathrm { SO } _ { 2 } > \mathrm { H } _ { 2 } \mathrm { S } > \mathrm { H } _ { 2 } \mathrm { S } _ { 2 } \mathrm { O } _ { 8 } {/tex}

Explanation



Q 7.    

Correct4

Incorrect-1

Which reaction does not represent autoredox or disproportionation:

A

{tex} \mathrm { Cl } _ { 2 } + \mathrm { OH } ^ { - } \longrightarrow \mathrm { Cl } ^ { - } + \mathrm { ClO } _ { 3 } ^ { - } + \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} 2 \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } \longrightarrow \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { O } _ { 2 } {/tex}

C

{tex} 2 \mathrm { Cu } ^ { + } \longrightarrow \mathrm { Cu } ^ { + 2 } + \mathrm { Cu } {/tex}

{tex} \left( \mathrm { NH } _ { 4 } \right) _ { 2 } \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } \longrightarrow \mathrm { N } _ { 2 } + \mathrm { Cr } _ { 2 } \mathrm { O } _ { 3 } + 4 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

Explanation

Q 8.    

Correct4

Incorrect-1

Which of the following is a redox reaction?

A

{tex} 2 \mathrm { CrO } _ { 4 } ^ { 2 - } + 2 \mathrm { H } ^ { + } \rightarrow \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } ^ { 2 - } + \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} \mathrm { CuSO } _ { 4 } + 4 \mathrm { NH } _ { 3 } \rightarrow \left[ \mathrm { Cu } \left( \mathrm { NH } _ { 3 } \right) _ { 4 } \right] \mathrm { SO } _ { 4 } {/tex}

{tex} \mathrm { Na } _ { 2 } \mathrm { S } _ { 2 } \mathrm { O } _ { 3 } + \mathrm { I } _ { 2 } \rightarrow \mathrm { Na } _ { 2 } \mathrm { S } _ { 4 } \mathrm { O } _ { 6 } + \mathrm { NaI } {/tex}

D

{tex} \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } ^ { 2 - } + 2 \mathrm { OH } ^ { - } \rightarrow 2 \mathrm { CrO } _ { 4 } ^ { 2 - } + \mathrm { H } _ { 2 } \mathrm { O } {/tex}

Explanation

Q 9.    

Correct4

Incorrect-1

In the reaction
{tex} x \mathrm { HI } + y \mathrm { HNO } _ { 3 } \longrightarrow \mathrm { NO } + \mathrm { I } _ { 2 } + \mathrm { H } _ { 2 } \mathrm { O } {/tex}

A

{tex} x = 3 , y = 2 {/tex}

B

{tex} x = 2 , y = 3 {/tex}

{tex} x = 6 , y = 2 {/tex}

D

{tex} x = 6 , y = 1 {/tex}

Explanation

Q 10.    

Correct4

Incorrect-1

For the redox reaction
\[ \mathrm { MnO } _ { 4 } ^ { - } + \mathrm { C } _ { 2 } \mathrm { O } _ { 4 } ^ { 2 - } + \mathrm { H } ^ { + } \longrightarrow \mathrm { Mn } ^ { 2 + } + \mathrm { CO } _ { 2 } + \mathrm { H } _ { 2 } \mathrm { O } \] the correct stoichiometric coefficients of {tex} \mathrm { MnO } _ { 4 } ^ { - } , \mathrm { C } _ { 2 } \mathrm { O } _ { 4 } ^ { 2 - } {/tex} and {tex} \mathrm { H } ^ { + } {/tex} are respectively

{tex} 2,5,16 {/tex}

B

{tex} 16.5,2 {/tex}

C

{tex} 5,16,2 {/tex}

D

{tex} 2,16,5 {/tex}

Explanation

Q 11.    

Correct4

Incorrect-1

Which of the following relations is incorrect?

A

{tex} 3 \mathrm { NAl } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } = 0.5 \mathrm { MAl } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex}

B

{tex} 3 \mathrm { M } \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } = 6 \mathrm { NH } _ { 2 } \mathrm { SO } _ { 4 } {/tex}

{tex} 1 \mathrm { M } \mathrm { H } _ { 3 } \mathrm { PO } _ { 4 } = 1 / 3 \mathrm { N } \mathrm { H } _ { 3 } \mathrm { PO } _ { 4 } {/tex}

D

{tex} 1 \mathrm { MAl } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } = 6 \mathrm { NAl } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex}

Explanation

Q 12.    

Correct4

Incorrect-1

In the reaction {tex} \mathrm { CrO } _ { 5 } + \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } \rightarrow \mathrm { Cr } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } + \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { O } _ { 2 } {/tex} one mole of {tex} \mathrm { CrO } _ { 5 } {/tex} will liberate how many moles of {tex} \mathrm { O } _ { 2 } ? {/tex}

A

{tex}5 / 2 {/tex}

B

{tex}5 / 4 {/tex}

C

{tex}9 / 2 {/tex}

{tex}7 / 4 {/tex}

Explanation

Q 13.    

Correct4

Incorrect-1

One gram of {tex} \mathrm { Na } _ { 3 } \mathrm { AsO } _ { 4 } {/tex} is boiled with excess of solid {tex} \mathrm { Kl } {/tex} in presence of strong HCl. The iodine evolved is absorbed in {tex} \mathrm { Kl } {/tex} solution and titrated against 0.2{tex} \mathrm { N } {/tex} hyposolution. Assuming the reaction to be
{tex} \mathrm { AsO } _ { 4 } ^ { 3 - } + 2 \mathrm { H } ^ { + } + 2 \mathrm { I } ^ { - } \longrightarrow \mathrm { AsO } _ { 3 } ^ { 3 - } + \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { I } _ { 2 } {/tex}
calculate the volume of thiosulphate hypo consumed. [Atomic weight of {tex} \mathrm { As } = 75 ] {/tex}

48.1{tex} \mathrm { mL } {/tex}

B

38.4{tex} \mathrm { mL } {/tex}

C

24.7{tex} \mathrm { mL } {/tex}

D

30.3{tex} \mathrm { mL } {/tex}

Explanation



Q 14.    

Correct4

Incorrect-1

25{tex} \mathrm { mL } {/tex} of 0.50{tex} \mathrm { M } \ \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} solution is added to 50{tex} \mathrm { mL } {/tex} of 0.20{tex} \mathrm { M } \ \mathrm { KMnO } _ { 4 } {/tex} in acid solution. Which of the following statement is true:

A

0.010 mole of oxygen is liberated.

0.005 mole of {tex} \mathrm { KMnO } _ { 4 } {/tex} are left.

C

0.030 g atom of oxygen gas is evolved.

D

0.0025 mole {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} does not react with {tex} \mathrm { KMnO } _ { 4 } {/tex}

Explanation

Q 15.    

Correct4

Incorrect-1

Hydrogen peroxide in aqueous solution decomposes on warming to give oxygen according to the equation{tex} 2 \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } ( \mathrm { aq } ) \longrightarrow 2 \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } ) + \mathrm { O } _ { 2 } ( \mathrm { g } ) {/tex}Under conditions where 1 mole of gas occupies 24 {tex} \mathrm { dm } ^ { 3 } \cdot 100 \mathrm { cm } ^ { 3 } {/tex} of {tex} \mathrm { XM } {/tex} solution of {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} produces 3{tex} \mathrm { dm } ^ { 3 } {/tex} of {tex} \mathrm { O } _ { 2 } {/tex} . Thus {tex} \mathrm { X } {/tex} is

2.5

B

1

C

0.5

D

0.25

Explanation

Q 16.    

Correct4

Incorrect-1

Temporary hardness is due to {tex} \mathrm { HCO } ^ { 3 - } {/tex} of {tex} \mathrm { Mg } ^ { 2 + } {/tex} and {tex} \mathrm { Ca } ^ { 2 + } {/tex} . It is removed by addition of {tex} \mathrm { CaO } {/tex} .
{tex} \mathrm { Ca } \left( \mathrm { HCO } _ { 3 } \right) _ { 2 } + \mathrm { CaO } \rightarrow 2 \mathrm { CaCO } _ { 3 } + \mathrm { H } _ { 2 } \mathrm { O } {/tex}
Mass of CaO required to precipitate {tex}2 \mathrm { g } \mathrm { CaCO } _ { 3 } {/tex} is

A

2

0.56{tex} g {/tex}

C

0.28{tex} g {/tex}

D

1.12{tex} { g } {/tex}

Explanation

Q 17.    

Correct4

Incorrect-1

Bottle (A) contains 320{tex} \mathrm { mL } {/tex} of {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} solution and la- belled with 10{tex} \ \mathrm{V} \ \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} and bottle (B) contains 80{tex} \mathrm { mL } {/tex} {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} having normality 5{tex} \mathrm { N } {/tex} . Bottle (A) and bottle (B) are mixed and solution filled in bottle (C). Select the correct label for bottle (C) in terms of volume strength and in terms of glitre.

{tex} 13.6 \, \mathrm {" V "} {/tex} and 41.285{tex} \mathrm { g } / \mathrm { L } {/tex}

B

{tex} 11.2 \, \mathrm {" V "} {/tex} and 0.68{tex} \mathrm { g } / \mathrm { L } {/tex}

C

{tex} 5.6 \, \mathrm {" V "} {/tex} and 0.68{tex} \mathrm { g } / \mathrm { L } {/tex}

D

{tex}5.6 \, {"V"}{/tex} and 41.285{tex} \mathrm { g } / \mathrm { L } {/tex}

Explanation

Q 18.    

Correct4

Incorrect-1

1 mol of iron (Fe) reacts completely with 0.65{tex} \mathrm { mol } \ \mathrm { O } _ { 2 } {/tex} to give a mixture of only {tex} \mathrm { FeO } {/tex} and {tex} \mathrm { Fe } _ { 2 } \mathrm { O } _ { 3 } . {/tex} Mole ratio of ferrous oxide to ferric oxide is

A

{tex} 3 : 2 {/tex}

{tex} 4 : 3 {/tex}

C

{tex} 20 : 13 {/tex}

D

none of these

Explanation

Q 19.    

Correct4

Incorrect-1

The molar ratio of {tex} \mathrm { Fe } ^ { + + } {/tex} to {tex} \mathrm { Fe } ^ { + + + } {/tex} in a mixture of {tex} \mathrm { FeSO } _ { 4 } {/tex} and {tex} \mathrm { Fe } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex} having equal number of sulphate ion in both ferrous and ferric sulphate is

A

{tex} 1 : 2 {/tex}

{tex} 3 : 2 {/tex}

C

{tex} 2 : 3 {/tex}

D

Cannot be determined

Explanation

Q 20.    

Correct4

Incorrect-1

If a piece of iron gains 10{tex} \% {/tex} of its weight due to partial rusting into {tex} \mathrm { Fe } _ { 2 } \mathrm { O } _ { 3 } {/tex} . The percentage of total iron that has rusted is

A

23

B

13

23.3

D

25.67

Explanation

Q 21.    

Correct4

Incorrect-1

{tex} \mathrm { HN } _ { } \mathrm { O } _ { 3 } {/tex} oxidises {tex} \mathrm { N } _ { } \mathrm { H } _ { 4 }^+ {/tex}

A

4

B

5

6

D

2

Explanation

Q 22.    

Correct4

Incorrect-1

25 {tex} \mathrm { mL } {/tex} of a 0.1{tex} \mathrm { M } {/tex} solution of a stable cation of transition metal {tex} \mathrm { Z } {/tex} reacts exactly with 25{tex} \mathrm { mL } {/tex} of 0.04{tex} \mathrm { mL } {/tex} acidified {tex} \mathrm { KMnO } _ { 4 } {/tex} solution. Which of the following is most likely to represent the change in oxidation state of Z correctly?

A

{tex} \mathrm { Z } ^ { + } \rightarrow \mathrm { Z } ^ { 2 + } {/tex}

B

{tex} \mathrm { Z } ^ { 3 + } \rightarrow \mathrm { Z } ^ { 1 + } {/tex}

C

{tex} Z ^ { 3 + } \rightarrow Z ^ { 4 + } {/tex}

{tex} \mathrm { Z } ^ { 2 + } \rightarrow \mathrm { Z } ^ { 4 + } {/tex}

Explanation

Q 23.    

Correct4

Incorrect-1

How many litres of {tex} \mathrm { Cl } _ { 2 } {/tex} at S.T.P. will be liberated by oxidation of {tex} \mathrm { NaCl } {/tex} with 10{tex} \mathrm { g } \ \mathrm { KMnO } _ { 4 } ? {/tex}

3.54{tex} \mathrm { L } {/tex}

B

7.08{tex} \mathrm { L } {/tex}

C

1.77{tex} \mathrm { L } {/tex}

D

None of these

Explanation



Q 24.    

Correct4

Incorrect-1

During the disproportionation of iodine to iodide and iodate ions, the ratio of iodate and iodide ions formed in alkaline medium is

{tex} 1 : 5 {/tex}

B

{tex} 5 : 1 {/tex}

C

{tex} 3 : 1 {/tex}

D

{tex} 1 : 3 {/tex}

Explanation

Q 25.    

Correct4

Incorrect-1

{tex} 28 \mathrm { NO } _ { 3 } ^ { - } + 3 \mathrm { As } _ { 2 } \mathrm { S } _ { 3 } + 4 \mathrm { H } _ { 2 } \mathrm { O } \rightarrow 6 \mathrm { AsO } _ { 4 } ^ { 3 - } + 28 \mathrm { NO } + 9 \mathrm { SO } _ { 4 } ^ { 2 - } + \mathrm { H } ^ { + } {/tex}
What will be the equivalent mass of {tex} \mathrm { As } _ { 2 } \mathrm { S } _ { 3 } {/tex} in above reaction?

A

{tex} \frac { \text { Molecular weight } } { 2 } {/tex}

B

{tex} \frac { \text { Molecular weight } } { 4 } {/tex}

C

{tex} \frac { \text { Molecular weight } } { 24 } {/tex}

{tex} \frac { \text { Molecular weight } } { 28 } {/tex}

Explanation