Redox Reaction – JEE Main Previous Year Questions with Solutions

JEE Main Previous Year Papers Questions of Chemistry With Solutions are available at eSaral.

Simulator

Previous Years AIEEE/JEE Mains Questions

Q. Consider the following reaction:

$\mathrm{xMnO}_{4}^{-}+\mathrm{yC}_{2} \mathrm{O}_{4}^{2-}+\mathrm{ZH}^{+} \rightarrow$

$\mathrm{xMn}^{2+}+2 \mathrm{yCO}_{2}+\frac{\mathrm{Z}}{2} \mathrm{H}_{2} \mathrm{O}$

The values of x, y and z in the reaction are respectively :-

(1) 5,2 and 16

(2) 2,5 and 8

(3) 2, 5 and 16

(4) 5,2 and 8

[JEE(Main)-2013]

Sol. (3)

Fact

Q. Given :

$\mathrm{X} \mathrm{Na}_{2} \mathrm{HAsO}_{3}+\mathrm{Y} \mathrm{NaBrO}_{3}+\mathrm{ZHCl} \rightarrow \mathrm{NaBr}$ $+\mathrm{H}_{3} \mathrm{AsO}_{4}+\mathrm{NaCl}$

The values of X, Y and Z in the above redox reaction are respectively :

(1) 2, 1, 3

(2) 3, 1, 6

(3) 2, 1, 2

(4) 3, 1, 4

[JEE(Main-online)-2013]

Sol. (2)

Fact

Q. In which of the following reaction $\mathrm{H}_{2} \mathrm{O}_{2}$ acts as a reducing agent ?

(1) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}$

(2) $\mathrm{H}_{2} \mathrm{O}_{2}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}^{+}$

(3) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{OH}^{-}$

(4) $\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{OH}^{-}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O}$

(1) (1), (3)

(2) (2), (4)

(3) (1), (2)

(4) (3), (4)

[JEE(Main-online)-2014]

Sol. (2)

Fact

Q. Consider the reaction

$\mathrm{H}_{2} \mathrm{SO}_{3(\mathrm{aq})}+\mathrm{Sn}_{(\mathrm{aq})}^{4+}+\mathrm{H}_{2} \mathrm{O}_{(\mathrm{l})} \rightarrow \mathrm{Sn}_{(\mathrm{aq})}^{2+}+\mathrm{HSO}_{4(\mathrm{aq})}^{-}+3 \mathrm{H}_{(\mathrm{aq})}^{+}$

Which of the following statements is correct?

(1) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes oxidation

(2) $\mathrm{H}_{2} \mathrm{SO}_{3}$ is the reducing agent because it undergoes reduction

(3) $\mathrm{Sn}^{4+}$ is the reducing agent because it undergoes oxidation

(4) $\mathrm{Sn}^{4+}$ is the oxidizing agent because it undergoes oxidation

[JEE(Main-online)-2014]

Sol. (1)

Fact

Q. How many electrons are involved in the following redox reaction ?

$\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathrm{Fe}^{2+}+\mathrm{C}_{2} \mathrm{O}_{4}^{2-} \rightarrow \mathrm{Cr}^{3+}+\mathrm{Fe}^{3+}+\mathrm{CO}_{2}$ (Unbalanced)

(1) 3 (2) 4 (3) 5 (4) 6

[JEE(Main-online)-2014]

Sol. (4)

Fact

Q. Which of the following reactions is an example of a redox reaction ?

(1) $\mathrm{XeF}_{4}+\mathrm{O}_{2} \mathrm{F}_{2} \rightarrow \mathrm{XeF}_{6}+\mathrm{O}_{2}$

(2) $\mathrm{XeF}_{2}+\mathrm{PF}_{5} \rightarrow[\mathrm{XeF}]^{+} \mathrm{PF}_{6}^{-}$

(3) $\mathrm{XeF}_{6}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{XeOF}_{4}+2 \mathrm{HF}$

(4) $\mathrm{XeF}_{6}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{XeO}_{2} \mathrm{F}_{2}+4 \mathrm{HF}$

[JEE-Main 2017]

Sol. (1)

In the reaction

$\stackrel{+4}{\mathrm{X}} \mathrm{e} \mathrm{F}_{4}+\mathrm{O}_{2} \mathrm{F}_{2} \rightarrow \stackrel{+6}{\mathrm{X}} \mathrm{eF}_{6}+\mathrm{O}_{2}^{0}$

Xenon undergoes oxidation while oxygen undergoes reduction.

Q. An alkali is titrated against an acid with methyl orange as indicator, which of the following is a correct combination ?

[JEE-Main 2018]

Sol. (2)

Methyl orange shows Red(pinkish) color in Acidic medium & yellow color in basic medium

since original solution is basic so

initial color  yellow

& Titrated with acid so

Final color  pinkish (red)