NEET > Redox Reactions

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


Q 1.    

Correct4

Incorrect-1

The brown ring complex is formulated as {tex} \left[ \mathrm { Fe } \left( \mathrm { H } _ { 2 } \mathrm { O } \right) _ { 5 } \mathrm { NO } \right] \mathrm { SO } _ { 4 } {/tex}. The oxidation number of iron is

1

B

2

C

3

D

0

Explanation

Q 2.    

Correct4

Incorrect-1

In which of the following reactions, there is no change in valency?

A

{tex} 4 \mathrm { KClO } _ { 3 } \rightarrow 3 \mathrm { KClO } _ { 4 } + \mathrm { KCl } {/tex}

B

{tex} \mathrm { SO } _ { 2 } + 2 \mathrm { H } _ { 2 } \mathrm { S } \rightarrow 2 \mathrm { H } _ { 2 } \mathrm { O } + 3 \mathrm { S } {/tex}

{tex} \mathrm { BaO } _ { 2 } + \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } \rightarrow \mathrm { BaSO } _ { 4 } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex}

D

{tex} 2 \mathrm { BaO } + \mathrm { O } _ { 2 } \rightarrow 2 \mathrm { BaO } _ { 2 } {/tex}

Explanation

Q 3.    

Correct4

Incorrect-1

The oxidation state of chromium in the final product formed by the reaction between KI and acidified potassium dichromate solution is:

{tex} + 3 {/tex}

B

{tex} + 2 {/tex}

C

{tex} + 6 {/tex}

D

{tex} + 4 {/tex}

Explanation

Q 4.    

Correct4

Incorrect-1

In which of the following pairs, there is greatest difference in the oxidation number of the underlined elements?

A

{tex} \mathrm{ \underline { N}{O } _ { 2 }} {/tex} and {tex} \mathrm{ \underline { N } _ { 2 } { O } _ { 4 } }{/tex}

B

{tex} \underline { \mathrm { P } } _ { 2 } \mathrm { O } _ { 5 } {/tex} and {tex} \underline { \mathrm { P } } _ { 4 } \mathrm { O } _ { 10 } {/tex}

C

{tex} \mathrm{\underline { N } _ { 2 } O} {/tex} and {tex} \mathrm{ \underline { N }O } {/tex}

{tex} \mathrm{ \underline { S } O_ { 2 } }{/tex} and {tex} \mathrm{ \underline { S}O_3 }{/tex}

Explanation

Q 5.    

Correct4

Incorrect-1

A compound of {tex} \mathrm {Xe} {/tex} and {tex} \mathrm { F } {/tex} is found to have {tex} 53.5 \% {/tex} of {tex} \mathrm {Xe } {/tex} . What is oxidation number of {tex} \mathrm { Xe } {/tex} in this compound?

A

{tex} - 4 {/tex}

B

{tex}0{/tex}

C

{tex} + 4 {/tex}

{tex} + 6 {/tex}

Explanation

Q 6.    

Correct4

Incorrect-1

Atomic number of an element is 22. The highest O.S. exhibited by it in its compounds is

A

1

B

2

C

3

4

Explanation

Q 7.    

Correct4

Incorrect-1

The reaction in which hydrogen peroxide acts as a reducing agent is

A

{tex} \mathrm { PbS } + 4 \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } \rightarrow \mathrm { PbSO } _ { 4 } + 4 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} 2 \mathrm { KI } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } \rightarrow 2 \mathrm { KOH } + \mathrm { I } _ { 2 } {/tex}

C

{tex} 2 \mathrm { FeSO } _ { 4 } + \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } \rightarrow \mathrm { Fe } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } + 2 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

{tex} \mathrm { Ag } _ { 2 } \mathrm { O } + \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } \rightarrow 2 \mathrm { Ag } + \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { O } _ { 2 } {/tex}

Explanation

Q 8.    

Correct4

Incorrect-1

Of the following reactions, only one is a redox reaction. Identify it

A

{tex} \mathrm { Ca } ( \mathrm { OH } ) _ { 2 } + 2 \mathrm { HCl } \rightarrow \mathrm { CaCl } _ { 2 } + 2 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} \mathrm { BaCl } _ { 2 } + \mathrm { MgSO } _ { 4 } \rightarrow \mathrm { BaSO } _ { 4 } + \mathrm { MgCl } _ { 2 } {/tex}

C

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

{tex} \mathrm { Cu } _ { 2 } \mathrm { S } + 2 \mathrm { FeO } \rightarrow 2 \mathrm { Cu } + 2 \mathrm { Fe } + \mathrm { SO } _ { 2 } {/tex}

Explanation

Q 9.    

Correct4

Incorrect-1

Arrange the following in the order of their decreasing electrode potentials : {tex} \mathrm { Mg } , \mathrm { K } , \mathrm { Ba } {/tex} and {tex} \mathrm { Ca } {/tex}

A

{tex} \mathrm { K } > \mathrm { Ca } > \mathrm { Ba } > \mathrm { Mg } {/tex}

B

{tex} \mathrm { Ba } > \mathrm { Ca } > \mathrm { K } > \mathrm { Mg } {/tex}

C

{tex} \mathrm { Ca } > \mathrm { Mg } > \mathrm { K } > \mathrm { Ba } {/tex}

{tex} \mathrm { Mg } > \mathrm { Ca } > \mathrm { Ba } > \mathrm { K } {/tex}

Explanation

Q 10.    

Correct4

Incorrect-1

Which of the following statements are correct concerning redox properties?
(i) A metal {tex} \mathrm { M } {/tex} for which {tex} \mathrm { E } ^ { \circ } {/tex} for the half life reaction {tex} \mathrm { M } ^ { \mathrm { n } + } + \mathrm { ne } ^ { - } \rightleftharpoons \mathrm { M } {/tex} is very negative will be a good reducing agent.
(ii) The oxidizing power of the halogens decreases from chlorine to iodine.
(iii) The reducing power of hydrogen halides increases from hydrogen chloride to hydrogen iodide

(i), (ii) and (iii)

B

(i) and (ii)

C

(i) only

D

(ii) and (iii)

Explanation

Q 11.    

Correct4

Incorrect-1

A negative {tex} \mathrm { E } ^ { \circ } {/tex} means that redox couple is a {tex} \underline{\mathrm A} {/tex} than the {tex} \mathrm { H } ^ { + } / \mathrm { H } _ { 2 } {/tex} couple
A positive {tex} \mathrm { E } ^ { \circ } {/tex} means that the redox couple is a {tex} \underline {\mathrm { B }} {/tex} than {tex} \mathrm { H } ^ { + } / \mathrm { H } _ { 2 } {/tex} couple

A

{tex} \mathrm { A } = {/tex} stronger reducing agent
{tex} \mathrm { B } = {/tex} weaker reducing agent

B

{tex} \mathrm { A } = {/tex} stronger oxidising agent
{tex} \mathrm { B } = {/tex} weaker oxidising agent

C

{tex} \mathrm { A } = {/tex} weaker oxidising agent
{tex} \mathrm { B } = {/tex} stronger oxidising agent

Both (a) and (c)

Explanation

Q 12.    

Correct4

Incorrect-1

If equal volume of reactants are used, then no. of moles of {tex} \mathrm { KMnO } _ { 4 } {/tex} (moles per litre) used in acidic medium required to completely oxidise {tex} 0.5 \mathrm { M } \ \mathrm { FeSO } _ { 3 } ? {/tex}

0.3

B

0.1

C

0.2

D

0.4

Explanation

Q 13.    

Correct4

Incorrect-1

If rod of a metal {tex} ( \mathrm { x } ) {/tex} is put in a metal ion solution which is blue in colour, solution turn colourless. The metal rod and solution respectively are?

A

{tex} \mathrm { Zinc } {/tex} and {tex} \mathrm { Cu } ( \mathrm { II } ) {/tex}

B

{tex} \mathrm {Zinc}{/tex} and {tex} \mathrm {{Ni}(II)}{/tex}

C

{tex}\mathrm {Aluminium}{/tex} and {tex}\mathrm {Cu (II)}{/tex}

Both (a) and (c)

Explanation

Q 14.    

Correct4

Incorrect-1

In the reaction between {tex} \mathrm { SO } _ { 2 } {/tex} and {tex} \mathrm { O } _ { 3 } {/tex} the equivalent weight of sulphur in product is

A

the same as its molecular weight

half of the molecular weight

C

one-third of the molecular weight

D

one-fourth of the molecular weight

Explanation

Q 15.    

Correct4

Incorrect-1

When {tex} \mathrm { KMnO } _ { 4 } {/tex} reacts with acidified {tex} \mathrm { FeSO } _ { 4 } {/tex}

{tex} \mathrm { FeSO } _ { 4 } {/tex} is oxidised and {tex} \mathrm { KMnO } _ { 4 } {/tex} is reduced

B

only {tex} \mathrm { KMnO } _ { 4 } {/tex} is oxidised

C

only {tex} \mathrm { FeSO } _ { 4 } {/tex} is oxidised

D

None of these

Explanation


Q 16.    

Correct4

Incorrect-1

Consider the following reaction
{tex} \mathrm { xMnO } _ { 4 } ^ { - } + \mathrm { yC } _ { 2 } \mathrm { O } _ { 4 } ^ { 2 - } + \mathrm { zH } ^ { + } \rightarrow \mathrm { xMn } ^ { 2 + } + 2 \mathrm { yCO } _ { 2 } + \frac { \mathrm { Z } } { 2 } \mathrm { H } _ { 2 } \mathrm { O } {/tex}
The value's of x, yand z in the reaction are, respectively:

A

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

B

{tex} 2, 5 {/tex} and {tex} 8 {/tex}

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

D

{tex} 5,2 {/tex} and {tex} 8 {/tex}

Explanation

Q 17.    

Correct4

Incorrect-1

When {tex} \mathrm { Cl } _ { 2 } {/tex} gas reacts with hot and concentrated sodium hydroxide solution, the oxidation number of chlorine changes from :

A

zero to {tex} + 1 {/tex} and zero to {tex} - 5 {/tex}

zero to {tex} - 1 {/tex} and zero to {tex} + 5 {/tex}

C

zero to {tex} - 1 {/tex} and zero to {tex} + 3 {/tex}

D

zero to {tex} + 1 {/tex} and zero to {tex} - 3 {/tex}

Explanation

Q 18.    

Correct4

Incorrect-1

Oxidation state for nitrogen is incorrectly given for compound oxidation state

{tex} \left[ \mathrm { Co } \left( \mathrm { NH } _ { 3 } \right) _ { 5 } \mathrm { Cl } \right] \mathrm { Cl } _ { 2 } \quad \quad\quad 0 {/tex}

B

{tex} \mathrm { NH } _ { 2 } \mathrm { OH } {/tex} {tex} \quad \quad \quad\quad\quad\quad -1 {/tex}

C

{tex} \left( \mathrm { N } _ { 2 } \mathrm { H } _ { 5 } \right) _ { 2 } \mathrm { SO } _ { 4 } {/tex} {tex} \quad \quad \quad\quad -2{/tex}

D

{tex} \mathrm { Mg } _ { 3 } \mathrm { N } _ { 2 } {/tex} {tex} \quad \quad \quad\quad\quad\quad -3 {/tex}

Explanation

Q 19.    

Correct4

Incorrect-1

Standard electrode potentials of redox couples {tex} \mathrm { A } ^ { 2 + } / \mathrm { A } , \mathrm { B } ^ { 2 + } / \mathrm { B } , \mathrm { C } ^ { 2 + } / \mathrm { C } {/tex} and {tex} \mathrm { D } ^ { 2 + } / \mathrm { D } {/tex} are {tex} 0.3 \mathrm { V } , - 0.5 \mathrm { V } , - 0.75 \mathrm { V } {/tex} and {tex} 0.9 \mathrm { V } {/tex} respectively. Which of these is best oxidising agent and reducing agent respectively-

A

{tex} \mathrm {D ^ { 2 + } / D} {/tex} and {tex} \mathrm {B ^ { 2 + } / B} {/tex}

B

{tex} \mathrm { B } ^ { 2 + } / \mathrm { B } {/tex} and {tex} \mathrm { D } ^ { 2 + } / \mathrm { D } {/tex}

{tex} \mathrm { D } ^ { 2 + } / \mathrm { D } {/tex} and {tex} \mathrm { C } ^ { 2 + } / \mathrm { C } {/tex}

D

{tex} \mathrm { C } ^ { 2 + } / \mathrm { C } {/tex} and {tex} \mathrm { D } ^ { 2 + } / \mathrm { D } {/tex}

Explanation

Q 20.    

Correct4

Incorrect-1

{tex} \mathrm { MnO } _ { 4 } ^ { 2 - } {/tex} (1 mole) in neutral aqueous medium disproportionates to

{tex} 2 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 4 } ^ { - } {/tex} and {tex} 1 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 2 } {/tex}

B

{tex} 1 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 4 } ^ { - } {/tex} and {tex} 2 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 2 } {/tex}

C

{tex} 1 / 3 {/tex} mole of {tex} \mathrm { Mn } _ { 2 } \mathrm { O } _ { 7 } {/tex} and {tex} 1 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 2 } {/tex}

D

{tex} 2 / 3 {/tex} mole of {tex} \mathrm { Mn } _ { 2 } \mathrm { O } _ { 7 } {/tex} and {tex} 1 / 3 {/tex} mole of {tex} \mathrm { MnO } _ { 2 } {/tex}

Explanation

Q 21.    

Correct4

Incorrect-1

In the standardization of {tex} \mathrm { Na } _ { 2 } \mathrm { S } _ { 2 } \mathrm { O } _ { 3 } {/tex} using {tex} \mathrm { K } _ { 2 } \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } {/tex} by iodometry, the equivalent weight of {tex} \mathrm { K } _ { 2 } \mathrm { Cr } _ { 2 } \mathrm { O } _ { 7 } {/tex} is

A

(molecular weight)/2

(molecular weight) /6

C

(molecular weight) / 3

D

same as molecular weight

Explanation

Q 22.    

Correct4

Incorrect-1

The species that undergoes disproportionation in an alkaline medium are

A

{tex} \mathrm { Cl } _ { 2 } {/tex}

B

{tex} \mathrm { MnO } _ { 4 } ^ { 2 - } {/tex}

C

{tex} \mathrm { NO } _ { 2 } {/tex}

All of these

Explanation

Q 23.    

Correct4

Incorrect-1

One mole of {tex} \mathrm { N } _ { 2 } \mathrm { H } _ { 4 } {/tex} loses {tex}10{/tex} moles of electrons to form a new compound y. Assuming that all nitrogen appear in the new compound, what is the oxidation state of nitrogen in y (There is no change in the oxidation state of hydrogen)

A

{tex} - 1 {/tex}

B

{tex} - 3 {/tex}

{tex} + 3 {/tex}

D

{tex} +5 {/tex}

Explanation

Q 24.    

Correct4

Incorrect-1

Phosphorus, sulphur and chlorine undergo disproportion in the .. A... medium. Here, A refers to

A

acidic

alkaline

C

neutral

D

Both (a) and (b)

Explanation

Q 25.    

Correct4

Incorrect-1

In which of the following compounds oxygen has highest oxidation state and in which it has lowest oxidation state? {tex} \mathrm { OF } _ { 2 } , \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } , \mathrm { KO } _ { 2 } , \mathrm { O } _ { 2 } \mathrm { F } _ { 2 } {/tex}

A

Highest {tex} = \mathrm { KO } _ { 2 } , {/tex} lowest {tex} = \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex}

B

Highest {tex} = \mathrm { OF } _ { 2 } , {/tex} lowest {tex} = \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex}

Highest {tex} = \mathrm { OF } _ { 2 } , {/tex} lowest {tex} = \mathrm { KO } _ { 2 } {/tex}

D

Highest {tex} = \mathrm { KO } _ { 2 } , {/tex} lowest {tex} = \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex}

Explanation