JEEChemistry

Redox Reactions

55 JEE Chemistry previous year questions on Redox Reactions — options free on every question; 6 include the answer & explanation free, the rest unlock with PYQ Pass.

Q1 FREE PREVIEW
PYQ

Volume of M/8 \(KMn{O}_{4}\) solution required to react completely with 25.0 \(c{m}^{3}\) of M/4 \(FeS{O}_{4}\) in acidic medium is:

a

8.0 mL

b

5.0 mL

c

15.0 mL

d

10.0 mL

✓ Correct answer: d)

10.0 mL

Explanation

The reaction is

\({\mathrm{MnO}}_{4}^{-}\) + 5Fe2+ + 8H+ → Mn2+ + 5Fe3+ + 4H₂O.

Using N₁V₁ = N₂V₂,

\(\frac{1}{8}\times 5{V}_{1}=\frac{1}{4}\times 25\)

Solving, V₁ = 10 mL.

Q2 FREE PREVIEW
PYQ

Chlorine undergoes disproportionation in alkaline medium as shown below:

\({\mathrm{aCl}}_{2}(\mathrm{g})+{\mathrm{bOH}}^{−}(\mathrm{aq})\to {\mathrm{cClO}}^{−}(\mathrm{aq})+{\mathrm{dCl}}^{−}(\mathrm{aq})+{\mathrm{eH}}_{2}\mathrm{O}(\mathrm{l})\)

The values of a, b, c and d in a balanced redox reaction are respectively:

a

1, 2, 1 and 1

b

2, 2, 1 and 3

c

3, 4, 4 and 2

d

2, 4, 1 and 3

✓ Correct answer: a)

1, 2, 1 and 1

Explanation

Balanced redox equation in alkaline medium:

Cl₂ + 2OH⁻ → ClO⁻ + Cl⁻ + H₂O

To balance:

Unbalanced form given in question:

aCl₂ + bOH⁻ → cClO⁻ + dCl⁻ + eH₂O

Balanced form:

a = 1, b = 2, c = 1, d = 1, e = 1

Hence, the correct option is: A (1, 2, 1, 1).

Q3 FREE PREVIEW
PYQ

The lowest oxidation number of an atom in a compound \(A _2 B\) is -2 . The number of electrons in its valence shell is _____

a

4

b

5

c

6

d

7

✓ Correct answer: c)

6

Explanation

\({A}_{2}B\to 2{A}^{+}+{B}^{−2},{B}^{−2}\) has complete octet in its dianionic form, thus in its atomic state it has 6 electrons in its valence shell. As it has negative charge, it has acquired two electrons to complete its octet.

Q4 FREE PREVIEW
PYQ

Which of the following reaction(s) is/are correct?

(a) \(F{e}^{3+}+{I}^{-}⟶{I}_{2}+F{e}^{2+}\)
(b) \(F{e}^{3+}+{I}^{-}⟶Fe{I}_{3}\)
(c) \(F{e}^{2+}+{S}_{2}{O}_{8}^{2-}⟶Fe+2S{O}_{4}^{2-}\)
(d) \(F{e}^{2+}+{S}_{2}{O}_{8}^{2-}⟶F{e}^{3+}+2S{O}_{4}^{2-}\)

a

(a) only

b

(b) and (c) only

c

(a) and (d) only

d

(b) and (d) only

✓ Correct answer: c)

(a) and (d) only

Explanation
  • (a) \(\mathrm{F}{\mathrm{e}}^{3+}\) oxidises \({\mathrm{I}}^{−}\) to \({\mathrm{I}}_{2}\) and itself gets reduced to \(\mathrm{F}{\mathrm{e}}^{2+}\) → correct redox reaction.

  • (b) \(\mathrm{F}\mathrm{e}{\mathrm{I}}_{3}\) is not stable in aqueous solution → incorrect.

  • (c) \(\mathrm{F}{\mathrm{e}}^{2+}\) cannot be reduced to Fe (0) by \({\mathrm{S}}_{2}{\mathrm{O}}_{8}^{2−}\) → incorrect.

  • (d) \({\mathrm{S}}_{2}{\mathrm{O}}_{8}^{2−}\)​ is a strong oxidant and oxidises \(\mathrm{F}{\mathrm{e}}^{2+}\) to \(\mathrm{F}{\mathrm{e}}^{3+}\) → correct.

Q5 FREE PREVIEW
PYQ

Chlorine undergoes disproportionation in alkaline medium as shown below:

\({\mathrm{aCl}}_{2}(\mathrm{g})+{\mathrm{bOH}}^{−}(\mathrm{aq})\to {\mathrm{cClO}}^{−}(\mathrm{aq})+{\mathrm{dCl}}^{−}(\mathrm{aq})+{\mathrm{eH}}_{2}\mathrm{O}(\mathrm{l})\)

The values of a, b, c and d in a balanced redox reaction are respectively:

a

1, 2, 1 and 1

b

2, 2, 1 and 3

c

3, 4, 4 and 2

d

2, 4, 1 and 3

✓ Correct answer: a)

1, 2, 1 and 1

Explanation

Balanced redox equation in alkaline medium:

Cl₂ + 2OH⁻ → ClO⁻ + Cl⁻ + H₂O

To balance:

Unbalanced form given in question:

aCl₂ + bOH⁻ → cClO⁻ + dCl⁻ + eH₂O

Balanced form:

a = 1, b = 2, c = 1, d = 1, e = 1

Hence, the correct option is: A (1, 2, 1, 1).

Q6 FREE PREVIEW
PYQ

In acidic medium, \(K _2 Cr _2 O _7\) shows oxidising action as represented in the half reaction

\[Cr _2 O _7{ }^{2-}+ XH ^{+}+ Ye ^{\ominus} \rightarrow 2 A + ZH _2 O\]

\(X , Y , Z\) and \(A\) are respectively

[JEE Main 2024, 01 Feb (Shift 1)]

a

\(14,7,6\) and \(Cr ^{3+}\)

b

\(8,6,4\) and \(Cr _2 O _3\)

c

\(8,4,6\) and \(Cr _2 O _3\)

d

\(14,6,7\) and \(Cr ^{3+}\)

✓ Correct answer: d)

\(14,6,7\) and \(Cr ^{3+}\)

Explanation

Given half-reaction in acidic medium:

Cr₂O₇²⁻ + XH⁺ + Ye⁻ → 2A + ZH₂O

We know standard reduction of dichromate in acidic medium:

Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O

Now comparing,

X = number of H⁺ = 14
Y = number of electrons = 6
Z = number of H₂O = 7
A = product formed = Cr³⁺

So values are:
X = 14, Y = 6, Z = 7, A = Cr³⁺

Q7
PYQ

In acidic medium, \(K _2 Cr _2 O _7\) shows oxidising action as represented in the half reaction

\[Cr _2 O _7{ }^{2-}+ XH ^{+}+ Ye ^{\ominus} \rightarrow 2 A + ZH _2 O\]

\(X , Y , Z\) and \(A\) are respectively

[JEE Main 2024, 01 Feb (Shift 1)]

a

\(14,7,6\) and \(Cr ^{3+}\)

b

\(8,6,4\) and \(Cr _2 O _3\)

c

\(8,4,6\) and \(Cr _2 O _3\)

d

\(14,6,7\) and \(Cr ^{3+}\)

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Q8
PYQ

Which of the following reaction(s) is/are correct?

(a) \(F{e}^{3+}+{I}^{-}⟶{I}_{2}+F{e}^{2+}\)
(b) \(F{e}^{3+}+{I}^{-}⟶Fe{I}_{3}\)
(c) \(F{e}^{2+}+{S}_{2}{O}_{8}^{2-}⟶Fe+2S{O}_{4}^{2-}\)
(d) \(F{e}^{2+}+{S}_{2}{O}_{8}^{2-}⟶F{e}^{3+}+2S{O}_{4}^{2-}\)

a

(a) only

b

(b) and (c) only

c

(a) and (d) only

d

(b) and (d) only

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Q9
PYQ

Which of the following cannot function as an oxidising agent?

[JEE Main 2024, 27 Jan (Shift 2)]

a

\(\mathrm{BrO}_{3}^{-}\)

b

\(\mathrm{MnO}_{4}^{-}\)

c

\(\mathrm{SO}_{4}^{2-}\)

d

\(\mathrm{N}^{3-}\)

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Q10
PYQ

Which of the following cannot function as an oxidising agent?

[JEE Main 2024, 27 Jan (Shift 2)]

a

\(\mathrm{BrO}_{3}^{-}\)

b

\(\mathrm{MnO}_{4}^{-}\)

c

\(\mathrm{SO}_{4}^{2-}\)

d

\(\mathrm{N}^{3-}\)

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Q11
PYQ

Which of the following cannot function as an oxidising agent?

[JEE Main 2024, 27 Jan (Shift 2)]

a

\(\mathrm{BrO}_{3}^{-}\)

b

\(\mathrm{MnO}_{4}^{-}\)

c

\(\mathrm{SO}_{4}^{2-}\)

d

\(\mathrm{N}^{3-}\)

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Q12
PYQ

Thiosulphate reacts differently with iodine and bromine in the reaction given below:

\(2{\text{S}}_{2}{{\text{O}}_{3}}^{2−}+{\text{I}}_{2}\to {\text{S}}_{4}{{\text{O}}_{6}}^{2−}+2{\text{I}}^{−}\)

\({\text{S}}_{2}{{\text{O}}_{3}}^{2−}+5{\mathrm{Br}}_{2}+5{\text{H}}_{2}\text{O}\to 2{\mathrm{SO}}_{4}^{2−}+4{\mathrm{Br}}^{−}+10{\text{H}}^{+}\)

Which of the following statement justifies the above dual behaviour of thiosulphate?

a

Bromine undergoes oxidation and iodine undergoes reduction by iodine in these reactions

b

Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reaction

c

Bromine is a stronger oxidant than iodine

d

Bromine is a weaker oxidant than iodine

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Q13
PYQ

From the given list, the number of compounds with +4 oxidation state of Sulphur is ___________.

\({\mathrm{SO}}_{3},{\mathrm{H}}_{2}{\mathrm{SO}}_{3},{\mathrm{SOCl}}_{2},{\mathrm{SF}}_{4},{\mathrm{BaSO}}_{4},{\mathrm{H}}_{2}{\mathrm{S}}_{2}{\mathrm{O}}_{7}\)

a

1

b

2

c

3

d

4

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Q14
PYQ

Volume of M/8 \(KMn{O}_{4}\) solution required to react completely with 25.0 \(c{m}^{3}\) of M/4 \(FeS{O}_{4}\) in acidic medium is:

a

8.0 mL

b

5.0 mL

c

15.0 mL

d

10.0 mL

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Q15
PYQ

Which of the following cannot function as an oxidising agent?

a

\({\text{N}}^{3−}\)

b

\({\text{SO}}_{4}^{2−}\)

c

\({\text{BrO}}_{3}^{−}\)

d

\({\text{MnO}}_{4}^{−}\)

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Q16
PYQ

Which of the following cannot function as an oxidising agent?

a

\({\text{N}}^{3−}\)

b

\({\text{SO}}_{4}^{2−}\)

c

\({\text{BrO}}_{3}^{−}\)

d

\({\text{MnO}}_{4}^{−}\)

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Q17
PYQ

Given below are two statements:
Statement I: In the oxalic acid vs \(KMn{O}_{4}\) (in the presence of dil \({H}_{2}S{O}_{4}\) ) titration the solution needs to be heated initially to \(60^\circ C\), but no heating is required in Ferrous ammonium sulphate (FAS) vs \(KMn{O}_{4}\) titration (in the presence of dil \({H}_{2}S{O}_{4}\) )

Statement II: In oxalic acid vs \(KMn{O}_{4}\) titration, the initial formation of \(MnS{O}_{4}\) takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs \(KMn{O}_{4}\), heating oxidizes \(F{e}^{2+}\) into \(F{e}^{3+}\) by oxygen of air and error may be introduced in the experiment.

In the light of the above statements, choose the correct answer from the options given below

[JEE Main 2025, 28 Jan (Shift 1)]

a

Statement I is false but Statement II is true

b

Both Statement I and Statement II are true

c

Both Statement I and Statement II are false

d

Statement I is true but Statement II is false

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Q18
PYQ

The species which does not undergo disproportionation reaction is

[JEE Main 2025, 22 Jan (Shift 2)]

a

\({{\mathrm{ClO}}_{4}}^{-}\)

b

\({\mathrm{ClO}}^{-}\)

c

\({{\mathrm{ClO}}_{2}}^{-}\)

d

\({{\mathrm{ClO}}_{3}}^{-}\)

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Q19
PYQ

Which of the following does not show disproportionation reaction? (memory based jee mains shift-2 22/01/2025)

a

\({\mathrm{ClO}}^{-}\)

b

\({{\mathrm{ClO}}_{2}}^{-}\)

c

\({\mathrm{ClO}}_{3}^{-}\)

d

\({\mathrm{ClO}}_{4}^{-}\)

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Q20
PYQ

Thiosulphate reacts differently with iodine and bromine in the reaction given below:

\(2{\text{S}}_{2}{{\text{O}}_{3}}^{2−}+{\text{I}}_{2}\to {\text{S}}_{4}{{\text{O}}_{6}}^{2−}+2{\text{I}}^{−}\)

\({\text{S}}_{2}{{\text{O}}_{3}}^{2−}+5{\mathrm{Br}}_{2}+5{\text{H}}_{2}\text{O}\to 2{\mathrm{SO}}_{4}^{2−}+4{\mathrm{Br}}^{−}+10{\text{H}}^{+}\)

Which of the following statement justifies the above dual behaviour of thiosulphate?

a

Bromine undergoes oxidation and iodine undergoes reduction by iodine in these reactions

b

Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reaction

c

Bromine is a stronger oxidant than iodine

d

Bromine is a weaker oxidant than iodine

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Q21
PYQ

Given below are two statements

Statement I: In the oxalic acid vs \(KMn{O}_{4}\) (in the presence of dil \({H}_{2}S{O}_{4}\) ) titration the solution needs to be heated initially to \(60^\circ C\), but no heating is required in Ferrous ammonium sulphate (FAS) vs \(KMn{O}_{4}\) titration (in the presence of dil \({H}_{2}S{O}_{4}\) )

Statement II: In oxalic acid vs \(KMn{O}_{4}\) titration, the initial formation of \(MnS{O}_{4}\) takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs \(KMn{O}_{4}\), heating oxidizes \(F{e}^{2+}\) into \(F{e}^{3+}\) by oxygen of air and error may be introduced in the experiment.

In the light of the above statements, choose the correct answer from the options given below.

[JEE Main 2025, 28 Jan (Shift 1)]

a

Statement I is false but Statement II is true

b

Both Statement I and Statement II are true

c

Both Statement I and Statement II are false

d

Statement I is true but Statement II is false

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Q22
PYQ

Which reaction is NOT a redox reaction?

a

\(BaC{l}_{2}+N{a}_{2}S{O}_{4}\to BaS{O}_{4}+2NaCl\)

b

\(Zn+CuS{O}_{4}\to ZnS{O}_{4}+Cu\)

c

\(2KCl{O}_{3}+{I}_{2}\to 2KI{O}_{3}+C{l}_{2}\)

d

\({H}_{2}+C{l}_{2}\to 2HCl\)

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Q23
PYQ

Given below are two statements:
Statement I: In the oxalic acid vs \(KMn{O}_{4}\) (in the presence of dil \({H}_{2}S{O}_{4}\) ) titration the solution needs to be heated initially to \(60^\circ C\), but no heating is required in Ferrous ammonium sulphate (FAS) vs \(KMn{O}_{4}\) titration (in the presence of dil \({H}_{2}S{O}_{4}\) )

Statement II: In oxalic acid vs \(KMn{O}_{4}\) titration, the initial formation of \(MnS{O}_{4}\) takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs \(KMn{O}_{4}\), heating oxidizes \(F{e}^{2+}\) into \(F{e}^{3+}\) by oxygen of air and error may be introduced in the experiment.

In the light of the above statements, choose the correct answer from the options given below

[JEE Main 2025, 28 Jan (Shift 1)]

a

Statement I is false but Statement II is true

b

Both Statement I and Statement II are true

c

Both Statement I and Statement II are false

d

Statement I is true but Statement II is false

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Q24
PYQ

The species which does not undergo disproportionation reaction is

[JEE Main 2025, 22 Jan (Shift 2)]

a

\({{\mathrm{ClO}}_{4}}^{-}\)

b

\({\mathrm{ClO}}^{-}\)

c

\({{\mathrm{ClO}}_{2}}^{-}\)

d

\({{\mathrm{ClO}}_{3}}^{-}\)

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Q25
PYQ

Thiosulphate reacts differently with iodine and bromine in the reaction given below:

\(2{\text{S}}_{2}{{\text{O}}_{3}}^{2−}+{\text{I}}_{2}\to {\text{S}}_{4}{{\text{O}}_{6}}^{2−}+2{\text{I}}^{−}\)

\({\text{S}}_{2}{{\text{O}}_{3}}^{2−}+5{\mathrm{Br}}_{2}+5{\text{H}}_{2}\text{O}\to 2{\mathrm{SO}}_{4}^{2−}+4{\mathrm{Br}}^{−}+10{\text{H}}^{+}\)

Which of the following statement justifies the above dual behaviour of thiosulphate?

a

Bromine undergoes oxidation and iodine undergoes reduction by iodine in these reactions

b

Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reaction

c

Bromine is a stronger oxidant than iodine

d

Bromine is a weaker oxidant than iodine

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Q26
PYQ

Chlorine undergoes disproportionation in alkaline medium as shown below

\(\mathrm{a}{\mathrm{Cl}}_{2}(\mathrm{g})+\mathrm{b}{\mathrm{OH}}^{-}(\mathrm{aq})\to \mathrm{c}{\mathrm{ClO}}_{3}^{−}(\mathrm{aq})+\mathrm{d}{\mathrm{Cl}}^{-}(\mathrm{aq})+\mathrm{e}{\mathrm{H}}_{2}\mathrm{O}(\mathrm{l})\)

The values of \(a, b, c\) and \(d\) in a balanced redox reaction are respectively

[JEE Main 2024, 29 Jan (Shift 1)]

a

2, 4, 1 and 3

b

3, 6, 1 and 5

c

3, 4, 4 and 2

d

2, 2, 1 and 3

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Q27
PYQ

Given below are two statements:
Statement I: In the oxalic acid vs \(KMn{O}_{4}\) (in the presence of dil \({H}_{2}S{O}_{4}\) ) titration the solution needs to be heated initially to \(60^\circ C\), but no heating is required in Ferrous ammonium sulphate (FAS) vs \(KMn{O}_{4}\) titration (in the presence of dil \({H}_{2}S{O}_{4}\) )

Statement II: In oxalic acid vs \(KMn{O}_{4}\) titration, the initial formation of \(MnS{O}_{4}\) takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs \(KMn{O}_{4}\), heating oxidizes \(F{e}^{2+}\) into \(F{e}^{3+}\) by oxygen of air and error may be introduced in the experiment.

In the light of the above statements, choose the correct answer from the options given below

[JEE Main 2025, 28 Jan (Shift 1)]

a

Statement I is false but Statement II is true

b

Both Statement I and Statement II are true

c

Both Statement I and Statement II are false

d

Statement I is true but Statement II is false

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Q28
PYQ

In which one of the following sets all species show disproportionation reaction?

[JEE Main 2021, 31 Aug (Shift 2)]

a

\(Mn{O}_{4}^{2-},Cl{O}_{2}^{-},C{l}_{2}\text{ and }M{n}^{3+}\)

b

\(Cl{O}_{2}^{-},{F}_{2},Mn{O}_{4}^{-}\text{and }C{r}_{2}{O}_{7}^{2-}\)

c

\(Cl{O}_{4}^{-},Mn{O}_{4}^{-},Cl{O}_{2}^{-}\text{and }{F}_{2}\)

d

\(C{r}_{2}{O}_{7}^{2-},Mn{O}_{4}^{-},Cl{O}_{2}^{-}\text{and }C{l}_{2}\)

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Q29
PYQ

When 10 mL of an aqueous solution of \(F{e}^{2+}\) ions was titrated in the presence of dil. \({H}_{2}S{O}_{4}\) using diphenylamine indicator, 15 mL of 0.02 M solution of \({K}_{2}C{r}_{2}{O}_{7}\) was required to get the end point. The molarity of the solution containing \(F{e}^{2+}\) ions is \(x\times {10}^{-2}M\) . The value of x is____ (Nearest integer)

[JEE Main 2021, 25 Jul (Shift 1)]

a

16

b

17

c

18

d

19

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Q30
PYQ

Which of the following equation depicts the oxidizing nature of \({\mathrm{H}}_{2}{\mathrm{O}}_{2}\) ?

[JEE Main 2021, 25 Feb (Shift 1)]

a

\({\mathrm{Cl}}_{2}+{\mathrm{H}}_{2}{\mathrm{O}}_{2}\to 2\mathrm{HCl}+{\mathrm{O}}_{2}\)

b

\({\mathrm{KIO}}_{4}+{\mathrm{H}}_{2}{\mathrm{O}}_{2}\to {\mathrm{KIO}}_{3}+{\mathrm{H}}_{2}\mathrm{O}+{\mathrm{O}}_{2}\)

c

\(2{\mathrm{I}}^{-}+{\mathrm{H}}_{2}{\mathrm{O}}_{2}+2{\mathrm{H}}^{+}\to {\mathrm{I}}_{2}+2{\mathrm{H}}_{2}\mathrm{O}\)

d

\({\mathrm{I}}_{2}+{\mathrm{H}}_{2}{\mathrm{O}}_{2}+2{\mathrm{OH}}^{-}\to 2{\mathrm{I}}^{-}+2{\mathrm{H}}_{2}\mathrm{O}+{\mathrm{O}}_{2}\)

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Q31
PYQ

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is:

a

3

b

4

c

5

d

6

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Q32
PYQ

Identify the process in which change in the oxidation state is five:

[JEE Main 2021, 25 Jul (Shift 2)]

a

\(Cr{O}_{4}^{2-}\to C{r}^{3+}\)

b

\(Mn{O}_{4}^{-}\to M{n}^{2+}\)

c

\(C{r}_{2}{O}_{7}^{2-}\to 2C{r}^{3+}\)

d

\({C}_{2}{O}_{4}^{2-}\to 2C{O}_{2}\)

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Q33
PYQ

Which of the following options are correct for the reaction?

\[2\left[\mathrm{Au}\left(\mathrm{CN}\right)_2\right]^{-}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s}) \rightarrow 2 \mathrm{Au}(\mathrm{s})+\left[\mathrm{Zn}(\mathrm{CN})_4\right]^{2-}(\mathrm{aq})\]

A. Redox reaction
B. Displacement reaction
C. Decomposition reaction
D. Combination reaction

Choose the correct answer from the options given below:

[JEE Main 2023, 6 Apr (Shift 1)]

a

A only

b

A and B only

c

A and D only

d

C and D only

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Q34
PYQ

For the reaction: \({\mathrm{NH}}_{3}+{\mathrm{OCl}}^{−}\to {\mathrm{N}}_{2}{\mathrm{H}}_{4}+{\mathrm{Cl}}^{−}\)in basic medium, the

coefficients of \({\mathrm{NH}}_{3},{\mathrm{OCl}}^{−}\mathrm{and}{\mathrm{N}}_{2}{\mathrm{H}}_{4}\) for the balanced equation are

respectively

a

2,2,2

b

2,2,1

c

2,1,1

d

4,4,2

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Q35
PYQ

Which of the following options are correct for the reaction
\[2\left[\mathrm{Au}\left(\mathrm{CN}\right)_2\right]^{-}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s}) \rightarrow 2 \mathrm{Au}(\mathrm{s})+\left[\mathrm{Zn}(\mathrm{CN})_4\right]^{2-}(\mathrm{aq})\]
A. Redox reaction
B. Displacement reaction
C. Decomposition reaction
D. Combination reaction

Choose the correct answer from the options given below:

[JEE Main 2023, 6 Apr (Shift 1)]

a

A only

b

A and B only

c

A and D only

d

C and D only

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Q36
PYQ

Given below are two statements

Statement-I: In redox titration, the indicators used are sensitive to change in pH of the solution.
Statement-II: In acid-base titration, the indicators used are sensitive to change in oxidation potential.

In the light of the above statements, choose the most appropriate answer from the options given below

[JEE Main 2023, 8 Apr (Shift 2)]

a

Both Statement-I and Statement-II are correct.

b

Statement-I is incorrect but Statement-II is correct.

c

Statement-I is correct but Statement-II is incorrect.

d

Both Statement-I and Statement-II are incorrect.

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Q37
PYQ

Which of the following is not a disproportionation reaction?

a

\({\mathrm{P}}_{4}+5{\mathrm{OH}}^{-}\to {\mathrm{H}}_{2}{{\mathrm{PO}}_{2}}^{-}\)

b

\({\mathrm{Cl}}_{2}+{\mathrm{OH}}^{-}\to {\mathrm{Cl}}^{-}+\mathrm{ClO}\)

c

\(2{\mathrm{H}}_{2}{\mathrm{O}}_{2}\to 2{\mathrm{H}}_{2}\mathrm{O}+{\mathrm{O}}_{2}\)

d

\({\mathrm{PbO}}_{2}+{\mathrm{H}}_{2}\mathrm{O}\to \mathrm{PbO}+{\mathrm{H}}_{2}{\mathrm{O}}_{2}\)

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Q38
PYQ

10.0 ml of 0.05 M KMnO4 solution was consumed in a titration with 10.0 mL of given oxalic acid dihydrate solution. The strength of given oxalic acid solution is ...... \(g/L\) (Round off to nearest integer)

[JEE Main 2021, 27 Jul (Shift 2)]

a

15

b

16

c

17

d

18

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Q39
PYQ

0.4 g mixture of \(NaOH,N{a}_{2}C{O}_{3}\) and some inert impurities was first titrated with \(\frac{N}{10}HCl\) using phenolphthalein as an indicator, 17.5 mL of HCl was required at the end point. After this methyl orange was added and titrated. 1.5 mL of same HCl was required for the next end point. The weight percentage of \(N{a}_{2}C{O}_{3}\) in the mixture is (Rounded off to the nearest integer)

[JEE Main 2021, 25 Feb (Shift 1)]

a

3

b

4

c

5

d

6

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Q40
PYQ

The species given below that does NOT show disproportionation reaction is:

[JEE Main 2021, 20 Jul (Shift 1)]

a

\(Br{O}^{-}\)

b

\(Br{O}_{3}^{-}\)

c

\(Br{O}_{2}^{-}\)

d

\(Br{O}_{4}^{-}\)

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Q41
PYQ

20 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of \({H}_{2}S{O}_{4}\). Also 20 mL standard solution of 0.5 M HCl containing 2 drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of 35.5 mL whereas the burette showed 25.5 mL initially. The concentration of \({H}_{2}S{O}_{4}\) is ____ M (Nearest integer)

[JEE Main 2023, 13 Apr (Shift 1)]

a

1

b

2

c

3

d

4

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Q42
PYQ

In basic medium \( \mathrm{CrO}_{4}^{2-} \) oxidises \( \mathrm{S}_{2} \mathrm{O}_{3}^{2-} \) to form \( \mathrm{SO}_{4}^{2-} \) and itself changes into \( \mathrm{Cr}(\mathrm{OH})_{4}^{-} \). The volume of \( 0.154 \mathrm{M} \mathrm{~CrO}_{4}^{2-} \) required to react with \( 40 \mathrm{~mL} \) of \( 0.25 \mathrm{M} \mathrm{~S}_{2} \mathrm{O}_{3}^{2-} \) is _______ \( \mathrm{mL} \).

(Rounded-off to the nearest integer)

a

173

b

175

c

177

d

179

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Q43
PYQ

On balancing the given redox reaction,
\({\mathrm{aCr}}_{2}{\mathrm{O}}_{7}^{2-}+{\mathrm{bSO}}_{3}^{2-}(\mathrm{aq})+{\mathrm{cH}}^{+}(\mathrm{aq})\to \\ 2{\mathrm{aCr}}^{3+}(\mathrm{aq})+{\mathrm{bSO}}_{4}^{2-}(\mathrm{aq})+\frac{\mathrm{c}}{2}{\mathrm{H}}_{2}\mathrm{O}(ℓ)\)

the coefficients \(\mathrm{a}, \mathrm{b}\) and \(\mathrm{c}\) are found to be, respectively -

a

3,8,1

b

1,8,3

c

8,1,3

d

1,3,8

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Q44
PYQ

The correct order of oxidation numbers of the metal ion in following oxides is:

(A) CrO3 (B) Fe2O3

(C) MnO2 (D) V2O5

(E) Cu2O

[JEE Main 2021, 25 Jul (Shift 1)]

a

(A) > (D) > (C) > (B) > (E)

b

(C) > (A) > (D) > (E) > (B)

c

(D) > (A) > (B) > (C) > (E)

d

(A) > (C) > (D) > (B) > (E)

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Q45
PYQ

Given below are two statements :
Statement-I: Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution.
Statement-II: In this titration phenolphthalein can be used as indicator.
In the light of the above statements, choose the most appropriate answer from the options given below:

[01 Feb, 2024 (Shift-I)]

a

Both Statement-I and Statement-II are correct

b

Statement-I is correct but Statement-II is incorrect

c

Statement-I is incorrect but Statement-II is correct

d

Both Statement-I and Statement-II are incorrect

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Q46
PYQ

The species given below that does not show disproportionation reaction is

[JEE Main 2021, 20 Jul (Shift 1)]

a

\(Br{O}^{-}\)

b

\(Br{O}_{3}^{-}\)

c

\(Br{O}_{2}^{-}\)

d

\(Br{O}_{4}^{-}\)

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Q47
PYQ

A \( 20.0 \mathrm{~mL} \) solution containing \( 0.2 \mathrm{~g} \) impure \( \mathrm{H}_{2} \mathrm{O}_{2} \) reacts completely with \( 0.316 \mathrm{~g} \) of \( \mathrm{KMnO}_{4} \) in acid solution. The purity of \( \mathrm{H}_{2} \mathrm{O}_{2} \) (in %) is ...........
(mol. wt. of \( \mathrm{H}_{2} \mathrm{O}_{2}=34 \); mol. wt. of \( \mathrm{KMnO}_{4}=158 \) )

a

81

b

83

c

85

d

87

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Q48
PYQ

In Chromyl chloride, the oxidation state of chromium is (+.......................)

[JEE Main 2023, 15 Apr (Shift 1)]

a

6

b

4

c

5

d

8

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Q49
PYQ

Match List-I with List-II:

List-I

(Reaction)

List-II

(Type of redox reaction)

(A)

N2(g)+O2(g) 2NO(g)

(I)

Decomposition

(B)

2Pb(NO3)2(s) 2PbO(s) + 4NO2(g)+O2(g)

(II)

Displacement

(C)

2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)

(III)

Disproportionation

(D)

2 NO2(g)+2OH(aq) \({\mathrm{NO}}_{2}^{-}\)(aq) + \({\mathrm{NO}}_{3}^{-}\)(aq) + H2O(l)

(IV)

Combination

Choose the correct answer from the options given below:

a

A-I, B-II, C-III, D-IV

b

A-III, B-II, C-I, D-IV

c

A-II, B-III, C-IV, D-I

d

A-IV, B-I, C-II, D-III

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Q50
PYQ

Consider the following molecules: \({\mathrm{Br}}_{3}{\mathrm{O}}_{8},{\mathrm{F}}_{2}\mathrm{O},{\mathrm{H}}_{2}{\mathrm{S}}_{4}{\mathrm{O}}_{6}\text{, }\)\({\mathrm{H}}_{2}{\mathrm{S}}_{5}{\mathrm{O}}_{6}\text{ and }{\mathrm{C}}_{3}{\mathrm{O}}_{2}\) Count the number of atoms existing in their zero oxidation state in each molecule. Their sum is

[JEE Advanced 2023, Paper-2]

a

4

b

5

c

6

d

7

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Q51
PYQ

The exact volumes of \(1\mathrm{M}\mathrm{NaOH}\) solution required to neutralize \(50\mathrm{mL}\text{of }1\mathrm{M}{\mathrm{H}}_{3}{\mathrm{PO}}_{3}\) solution and 100 mL of \(2\mathrm{M}{\mathrm{H}}_{3}{\mathrm{PO}}_{2}\), solution respectively, are

[JEE Main 2021, 16 Mar (Shift 2)]

a

100 ml and 50 ml

b

100 ml and 200 ml

c

50 ml and 50 ml

d

100 mL and 100 mL

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Q52
PYQ

In basic medium, \({\mathrm{H}}_{2}{\mathrm{O}}_{2}\) exhibits which of the following reactions?
(A) \({\mathrm{Mn}}^{2+}⟶{\mathrm{Mn}}^{4+}\)
(B) \({\mathrm{I}}_{2}⟶{\mathrm{I}}^{-}\)
(C) \(\mathrm{PbS}⟶{\mathrm{PbSO}}_{4}\)

Choose the most appropriate answer from the options given below:

[JEE Main 2021, 18 Mar (Shift 2)]

a

(A), (C) only

b

(B) only

c

(A), (B) only

d

(A) only

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Q53
PYQ

Given below are two statements:

Statement-I: S8 solid undergoes disproportionation reaction under alkaline conditions to form S2– and \({\mathrm{S}}_{2}{{\mathrm{O}}_{3}}^{2−}\)

Statement-II: \({\mathrm{ClO}}_{4}^{−}\) can undergo disproportionation reaction under acidic condition.

In the light of the above statements, choose the most appropriate answer from the options given below:

[JEE Main 2024, 31 Jan (Shift 2)]

a

Statement-I is correct but statement-II is incorrect

b

Statement-I is incorrect but statement-II is correct

c

Both statement-I and statement-II are incorrect

d

Both statement-I and statement-II are correct

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Q54
PYQ

See the following chemical reaction:
\(C{r}_{2}{O}_{7}^{2-}+X{H}^{+}+6F{e}^{2+}\to YC{r}^{3+}\)\(+6F{e}^{3+}+Z{H}_{2}O\)

The sum of \(X, Y\) and \(Z\) is

[JEE Main 2023, 13 Apr (Shift 2)]

a

21

b

22

c

23

d

24

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Q55
PYQ

The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are \(x, y\) and \(z\). The sum of \(x, y\) and \(z\) is, \(\mathrm{Na}_4\left[\mathrm{Fe}(\mathrm{CN})_5(\mathrm{NOS})\right]\) , \(\mathrm{Na}_4\left[\mathrm{FeO}_4\right]\) , \(\left[\mathrm{Fe}_2(\mathrm{CO})_9\right]\)

[JEE Main 2020, 2 Sep (Shift 1)]

a

3

b

4

c

5

d

6

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