Redox Reactions · Chemistry · COMEDK

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MCQ (Single Correct Answer)

1

In the redox reaction, taking place in acidic medium: $\mathrm{X} \mathrm{MnO}_4^{-}(\mathrm{aq})+\mathrm{YSO}_2(\mathrm{~g}) \rightarrow \mathrm{Mn}^{+2}(\mathrm{aq})+\mathrm{HSO}_4^{-}(\mathrm{aq})$, the ratio of $X: Y$ in a stoichiometrically balanced equation will be

COMEDK 2026 Afternoon Shift
2

$x$ moles of $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ oxidises 1 mole of ferrous oxalate, in acidic medium. Hence ' $x$ ' is:

COMEDK 2026 Afternoon Shift
3

In the reaction,

$$ \mathrm{Cr}_2 \mathrm{O}_7^{2-}+4 \mathrm{H}_2 \mathrm{O}_2+2 \mathrm{H}^{+} \rightarrow 2 \mathrm{CrO}_5+\mathrm{H}_2 \mathrm{O} $$

The change in oxidation state of Cr is:

COMEDK 2026 Morning Shift
4

Identify the correct coefficients (a), (b), (c) and (d) in the following equations

i) $\quad \mathrm{xMnO}_4^{--}+$(a) $\mathrm{SO}_3{ }^{2-}+$ (b) $\mathrm{H}^{+} \cdots \longrightarrow \mathrm{xMn}^{2+}+$ (a) $\mathrm{SO}_4{ }^{2-}+$ (c) $\mathrm{H}_2 \mathrm{O}$

ii) (c) $\mathrm{S}_2 \mathrm{O}_3{ }^{2-}+$ (d) $\mathrm{MnO}_4^{-}+\mathrm{H}_2 \mathrm{O} \cdots \rightarrow$ (d) $\mathrm{MnO}_2+$ (b) $\mathrm{SO}_4{ }^{2-}+\mathrm{xOH}^{-}$

COMEDK 2025 Evening Shift
5
An example of disproportionation reaction is :
COMEDK 2025 Evening Shift
6
The oxidation number of potassium in $\mathrm{K}_2 \mathrm{O}, \mathrm{K}_2 \mathrm{O}_2$ and $\mathrm{KO}_2$ respectively are:
COMEDK 2025 Evening Shift
7

Given below are 2 statements: one Assertion and the other Reason. Which one of the following options is correct?

Assertion : Sulphur dioxide and Hydrogen peroxide can act as both oxidising and reducing agents but Nitric acid can act as only oxidising agent.

Reason : Sulphur and Oxygen can exhibit more than one stable oxidation states while Nitrogen does not.

COMEDK 2025 Afternoon Shift
8
Choose the correct statement.
COMEDK 2025 Morning Shift
9
The concentration and percentage purity of Oxalic acid can be determined by titration with $\mathrm{KMnO}_4$ in presence of dil. $\mathrm{H}_2 \mathrm{SO}_4$. Instead of dil. $\mathrm{H}_2 \mathrm{SO}_4$, dil HCl cannot be used because
COMEDK 2025 Morning Shift
10

Which one of the following options represents the decreasing order of oxidation number of the central atom in:

$$\mathrm{Cr}_2 \mathrm{O}_7^{2-}, \mathrm{Cr} \mathrm{O}_2^{-}, \mathrm{MnO}_4^{-}, \mathrm{BrO}_3^{-}$$

COMEDK 2025 Morning Shift
11

In the redox reaction between $$\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{H}^{+}$$ and sulphite ion, what is the number of moles of electrons involved in producing 3.0 moles of the oxidised product?

COMEDK 2024 Evening Shift
12

In the reaction,

$$2 \mathrm{~S}_2 \mathrm{O}_3^{2-}+\mathrm{I}_2 \rightarrow \mathrm{S}_4 \mathrm{O}_6^{2-}+2 \mathrm{I}^{-}$$

COMEDK 2024 Afternoon Shift
13

When $$3.92 \mathrm{~g}$$ of Mohr salt is dissolved in $$100 \mathrm{~mL}$$ of water, and titrated against $$\mathrm{KMnO}_4$$ solution, $$20 \mathrm{~mL}$$ of this solution required $$18 \mathrm{~mL}$$ of $$\mathrm{KMnO}_4$$ for complete oxidation. The strength of $$\mathrm{KMnO}_4$$ is: [Molar mass of Mohr salt is $$392 \mathrm{~g} \mathrm{~mol}^{-1}$$ and $$\mathrm{KMnO}_4$$ is $$158 \mathrm{~g} \mathrm{~mol}^{-1}$$]

COMEDK 2024 Afternoon Shift
14

Identify the oxidation reaction in which acidified $$\mathrm{KMnO}_4$$ is required

COMEDK 2024 Afternoon Shift
15

An inorganic salt comprises of atoms of elements $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$. If the oxidation numbers of A, B and $$\mathrm{C}$$ are $$+3,+6$$ and $$-$$2 respectively, what is the possible formula of the compound?

COMEDK 2024 Morning Shift
16

Choose the group of ions / molecules in which none of the species undergo Disproportionation reaction.

COMEDK 2024 Morning Shift
17

In dilute alkaline solution $$\mathrm{MnO}_4^{-}$$ changes to

COMEDK 2023 Morning Shift
18

In neutral medium $$\mathrm{KMnO}_4$$ oxidises $$\mathrm{MnSO}_4$$ to _________

COMEDK 2023 Evening Shift
19

In the given Redox equation, identify the stoichiometric coefficients $$\mathrm{w}, \mathrm{x}, \mathrm{y}$$ and $$\mathrm{z}$$.

$$\mathrm{ClO}_3^{-1}+\mathrm{w} \mathrm{Cl}^{-1}+\mathrm{xH}^{+} \rightarrow \mathrm{y} \mathrm{H}_2 \mathrm{O}+\mathrm{zCl}_2$$

COMEDK 2023 Evening Shift
20

Identify the catalyst used in the reaction between Iodide and persulphate ions.

$$2 \mathrm{I}^{-}+\mathrm{S}_2 \mathrm{O}_8{ }^{2-} \rightarrow \mathrm{I}_2+2 \mathrm{SO}_4{ }^{2-}$$

COMEDK 2023 Evening Shift
21

KMnO$$_4$$ acts as an oxidising agent in acidic medium. The number of moles of KMnO$$_4$$ that will be required to react with one mole of oxalate ions (to form CO$$_2$$) in acidic solution is

COMEDK 2022
22

Which of the following gas readily de-colourises the acidified KMnO$$_4$$ solution?

COMEDK 2022
23

The oxidation number of Cr in CrO$$_5$$ which has the following structure, is

COMEDK 2021 Chemistry - Redox Reactions Question 25 English

COMEDK 2021
24

For decolourisation of 1 mole of KMnO$$_4$$, the moles of H$$_2$$O$$_2$$ required is

COMEDK 2021
25

In the ionic equation,

$$\mathrm{BiO_3^-+6H^++xe^-\rightarrow Bi^{3+}+3H_2O}$$,

the value of x is

COMEDK 2020
26

Carbon forms two oxides which have different compositions. The equivalent mass of which remains constant?

COMEDK 2020