Redox Reactions - Physical Chemistry - Chemistry Previous Year Questions

1

2003 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2003

The oxidation states of sulphur in the anions

SO3\({_3^{2 - }}\), S₂O\({_4^{2 - }}\) and S₂O\({_6^{2 - }}\) follow the order

A

S₂O\({_4^{2 - }}\) < SO\({_3^{2 - }}\) < S₂O\({_6^{2 - }}\)

B

SO\({_3^{2 - }}\) < S₂O\({_4^{2 - }}\) < S₂O\({_6^{2 - }}\)

C

S₂O\({_4^{2 - }}\) < S₂O\({_6^{2 - }}\) < SO\({_3^{2 - }}\)

D

S₂O\({_6^{2 - }}\) < S₂O\({_4^{2 - }}\) < SO\({_3^{2 - }}\)

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2

2004 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2004

Which is the best description of the behaviour of bromine in the reaction given below?
H₂O + Br₂ \(\to\) HOBr + HBr

A

Proton acceptor only

B

Both oxidised and reduced

C

Oxidised only

D

Reduced only

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3

2008 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2008

Number of moles of MnO\(_4^{ - }\) required to oxidize one mole of ferrous oxalate completely in acidic medium will be

A

7.5 moles

B

0.2 moles

C

0.6 moles

D

0.4 moles

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4

2009 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2009

Oxidation numbers of P in PO\(_4^{3 - }\), of S in SO\(_4^{2 - }\) and that of Cr in Cr₂O\(_7^{2 - }\) are respectively

A

+3, +6 and +5

B

+5, +3 and +6

C

\(-\)3, +6 and + 6

D

+5, +6 and +6

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5

2012 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2012 PRELIMS

A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?

A

S

B

H

C

Cl

D

C

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6

2012 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2012 PRELIMS

When Cl₂ gas reacts with hot and concentrated sodium hydroxide solution, the oxidation number of chlorine changes from

A

zero to +1 and zero to \(-\)5

B

zero to \(-\)1 and zero to +5

C

zero to \(-\)1 and zero to +3

D

zero to +1 and zero to \(-\)3

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7

2014 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2014

In acidic medium, H₂O₂ changes Cr₂O₇^2- to CrO₅ which has two

(\(-\)O\(-\)O\(-\)) bonds. Oxidation state of Cr in CrO₅ is

A

+5

B

+3

C

+6

D

\(-\)10

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8

2014 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2014

(I)   H₂O₂ + O₃ \(\to\) H₂O + 2O₂
(II)   H₂O₂ + Ag₂O \(\to\) 2Ag + H₂O + O₂
Role of Hydrogen peroxide in the above reactions is respectvely

A

oxidizing in (I) and reducing in (II)

B

reducing in (I) and oxidizing (II)

C

reducing in (I) and (II)

D

oxidizing in (I) and (II)

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9

2014 · Chemistry · Physical Chemistry · Redox Reactions

AIPMT 2014

The pair of compounds that can exist together is

A

FeCl₃, SnCl₂

B

HgCl₂, SnCl₂

C

FeCl₂, SnCl₂

D

FeCl₃, KI

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10

2016 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2016 PHASE 2

Hot concentrated sulphate acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour?

A

Cu + 2H₂SO₄ \(\to\) CuSO₄ + SO₂ + 2H₂O

B

S + 2H₂SO₄ \(\to\) 3SO₂ + 2H₂O

C

C + 2H₂SO₄ \(\to\) CO₂ + 2SO₂ + 2H₂O

D

CaF₂ + H₂SO₄ \(\to\) CaSO₄ + 2HF

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11

2018 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2018

The correct order of N-compounds in its decreasing order of oxidation states is

A

HNO₃ , NO, N₂ , NH₄Cl

B

HNO₃ , NO, NH₄Cl, N₂

C

HNO₃ , NH₄Cl, NO, N

D

NH₄Cl, N₂ , NO, HNO₃

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12

2018 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2018

For the redox reaction,
MnO₄^– + C₂O₄ ^2– + H⁺ \(\to\) Mn²⁺ + CO₂ + H₂O
The correct coefficients of the reactants for the balanced equation are

A

MnO4-	C2O42-	H+
16	5	2

B

MnO4-	C2O42-	H+
2	5	16

C

MnO4-	C2O42-	H+
2	16	5

D

MnO4-	C2O42-	H+
5	16	2

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13

2019 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2019

Which of the following reactions are disproportionation reaction?

(a) 2Cu⁺ \(\to\) Cu²⁺ + Cu⁰
(b) 3MnO₄^2- + 4H⁺ \(\to\) 2MnO₄^- + MnO₂ + 2H₂O
(c) 2KMnO₄ \(\buildrel \Delta \over \longrightarrow\) K₂MnO₄ + MnO₂ + O₂
(d) 2MnO₄^- + 3Mn²⁺ + 2H₂O \(\to\) 5MnO₂ + 4\({H^ \oplus }\)

Select the correct option from the following :

A

(a), (c) and (d)

B

(a) and (b) only

C

(a) and (d) only

D

(a), (b) and (c)

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14

2020 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2020 PHASE 1

What is the change in oxidation number of carbon in the following reaction?
CH₄(g) + 4Cl₂(g) \(\to\) CCl₄(l) + 4HCl(g)

A

0 to + 4

B

\(-\)4 to + 4

C

0 to \(-\) 4

D

+ 4 to + 4

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15

2022 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2022 PHASE 2

Which of the following reactions is a decomposition redox reaction?

A

P₄(s) + 3OH^\(-\)(aq) + 3H₂O(l) \(\to\) PH₃(g) + 3H₂PO\(_2^ -\)(aq)

B

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

C

N₂(g) + O₂(g) \(\to\) 2NO(g)

D

Cl₂(g) + 2OH^\(-\)(aq) \(\to\) ClO^\(-\)(aq) + Cl^\(-\)(aq) + 4H₂O(l)

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16

2023 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2023

On balancing the given redox reaction,

$$\mathrm{aCr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{bSO}_{3}^{2-}(\mathrm{aq})+\mathrm{cH}^{+}(\mathrm{aq}) \rightarrow 2 \mathrm{aCr}^{3+}(\mathrm{aq})+\mathrm{bSO}_{4}^{2-}(\mathrm{aq})+\frac{\mathrm{c}}{2} \mathrm{H}_{2} \mathrm{O}(\ell)$$

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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17

2023 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2023 MANIPUR

The correct option for a redox couple is:

A

Both are oxidised forms involving same element.

B

Both are reduced forms involving same element.

C

Both the reduced and oxidised forms involve same element.

D

Cathode and anode together.

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18

2024 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2024

Which reaction is NOT a redox reaction?

A

\(\mathrm{Zn}+\mathrm{CuSO}_4 \rightarrow \mathrm{ZnSO}_4+\mathrm{Cu}\)

B

\(2 \mathrm{KClO}_3+\mathrm{I}_2 \rightarrow 2 \mathrm{KIO}_3+\mathrm{Cl}_2\)

C

\(\mathrm{H}_2+\mathrm{Cl}_2 \rightarrow 2 \mathrm{HCl}\)

D

\(\mathrm{BaCl}_2+\mathrm{Na}_2 \mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4+2 \mathrm{NaCl}\)

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19

2024 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2024 RE EXAMINATION

The oxidation states not shown by Mn in given reaction is :

$$3 \mathrm{MnO}_4^{2-}+4 \mathrm{H}^{+} \longrightarrow 2 \mathrm{MnO}_4^{-}+\mathrm{MnO}_2+2 \mathrm{H}_2 \mathrm{O}$$

A. +6

B. +2

C. +4

D. +7

E. +3

Choose the most appropriate answer from the options given below :

A

D and E only

B

B and D only

C

A and B only

D

B and E only

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20

2025 · Chemistry · Physical Chemistry · Redox Reactions

NEET 2025

Consider the following compounds :

${\mathrm{\underline{K}O}}_2, \mathrm{H}_2 \underline{\mathrm{O}}_2$ and $\mathrm{H}_2 \underline{S }O_4$

The oxidation state of the underlined elements in them are, respectively,

A

$+1,-2$, and +4

B

$+4,-4$, and +6

C

$+1,-1$, and +6

D

$+2,-2$, and +6

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