# JEE Main

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

## Mathematics

Redox Reactions

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Q 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

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Q 2. 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

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Q 3. 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

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Q 4. 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

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Q 5. 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

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Q 6. 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

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Q 7. 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

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Q 8. 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

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Q 9. 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

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Q 10. 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\space \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

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Q 11. 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

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Q 12. 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

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Q 13. Bottle (A) contains 320{tex} \mathrm { mL } {/tex} of {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} solution and labelled 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 {tex} \mathrm {41.285 g } / \mathrm { L } {/tex}

B

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

C

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

D

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

##### Explanation

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Q 14. 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