1. ⇒ (MHT CET 2023 12th May Evening Shift )

What is the change in oxidation number of $Cr$ in the following redox reaction?

$3 H_{2} O_{2 (aq)} + {Cr}_{2} O_{7 (aq)}^{2 -} + 8 H_{(aq)}^{+} ⟶ 3 O_{2 (g)} + 2 {Cr}^{3} + 7 H_{2} O$

A. +2 to +3

B. $-$ 2 to +3

C. +7 to +3

D. +6 to +3

Correct Option is (D)

MHT CET 2023 12th May Evening Shift Chemistry - Redox Reactions Question 1 English Explanation

2. ⇒ (MHT CET 2023 11th May Evening Shift )

What is the oxidation number of sulfur in $H_{2} {SO}_{5}$ ?

A. +4

B. +6

C. +8

D. +5

Correct Option is (B)

$H_{2} {SO}_{5} : Peroxymonosulfuric acid$

MHT CET 2023 11th May Evening Shift Chemistry - Redox Reactions Question 4 English Explanation

It has a peroxide linkage.

$\begin{aligned} (2 \times 1) + x + (3 \times - 2) + (2 \times - 1) = 0 \\ ∴ & x = + 6 \end{aligned}$

3. ⇒ (MHT CET 2023 10th May Evening Shift )

Identify the elements undergoing reduction and oxidation respectively in the following redox reaction.

$3 H_{3} {AsO}_{3 (aq)} + {BrO}_{3 (aq)}^{-} \to {Br}_{(aq)}^{-} + 3 H_{3} {AsO}_{4}$

A. As and $O$

B. $Br$ and $As$

C. $As$ and $Br$

D. $Br$ and $O$

Correct Option is (B)

The oxidation number of $Br$ decreases from +5 to $-$ 1 and that of As increases from +3 to +5.

Hence, $Br$ undergoes reduction and $As$ undergoes oxidation.

4. ⇒ (MHT CET 2023 10th May Morning Shift )

What is the value of $x$ in order to balance following redox reaction?

${Mn}_{(aq)}^{2 +} + x {ClO}_{3 (aq)}^{-} \to {MnO}_{2 (s)} + x {ClO}_{2 (aq)}$

A. $x = 1$

B. $x = 2$

C. $x = 3$

D. $x = 4$

Correct Option is (B)

The balanced equation is:

${Mn}_{(aq)}^{2 +} + 2 {ClO}_{3 (sq)} \to {MnO}_{2 (s)} + 2 {ClO}_{2 (aq)}$

5. ⇒ (MHT CET 2023 9th May Morning Shift )

What is the oxidation state of carbon in ${CaC}_{2}$ and $K_{2} C_{2} O_{4}$ respectively?

A. $- 2$ and $+ 6$

B. $- 1$ and $+ 3$

C. $+ 2$ and $+ 2$

D. $- 2$ and $+ 3$

Correct Option is (B)

$\begin{array}{ll} {CaC}_{2} \\ ∴ & + 2 + (x \times 2) = 0 or x = - 1 \\ K_{2} C_{2} O_{4} \\ ∴ & (+ 1 \times 2) + (x \times 2) + (- 2 \times 4) = 0 or x = + 3 \end{array}$

⇒Redox Reaction