6. ⇒ (MHT CET 2021 21th September Morning Shift )

Oxidation state of Cr in potassium dichromate is

A. +7

B. +6

C. +1

D. +5

Correct Option is (B)

Potassium dichromate $\to K_{2} {Cr}_{2} O_{7}$ Consider, oxidation state of $Cr$ is $X$ .

$\begin{aligned} K_{2} {Cr}_{2} O_{7} \to & 2 (+ 1) + 2 (x) + 7 (- 2) = 0 \\ ∴ & 2 + 2 x - 14 = 0 \\ 2 x = 12 \\ ∴ & x = + 6 \end{aligned}$

$∴$ Oxidation state of $Cr = + 6$

7. ⇒ (MHT CET 2021 20th September Evening Shift )

What is the value of ' $x$ ' in order to balance the following redox reaction by ion electron method? $x H_{2} O_{2} + {ClO}_{4} \to {xO}_{2} + {ClO}_{2} + 2 H_{2} O$

A. 3

B. 4

C. 1

D. 2

Correct Option is (D)

$2 H_{2} O_{2} + {ClO}_{4}^{⊖} ⟶ 2 O_{2} + {ClO}_{2}^{⊖} + 2 H_{2} O$

8. ⇒ (MHT CET 2021 20th September Morning Shift )

Identify reductant in following reaction.

$C_{2} O_{4}^{2 -} + {MnO}_{4}^{-} + H^{+} ⟶ M n^{2 +} + C O_{2} + H_{2} O$

A. $H^{+}$

B. $H_{2} O$

C. $C_{2} O_{4}^{2 -}$

D. $M n O_{4}^{-}$

Correct Option is (C)

MHT CET 2021 20th September Morning Shift Chemistry - Redox Reactions Question 8 English Explanation

The oxidation number of C increases from $+ 3 (C_{2} O_{4}^{2 -})$ to $+ 4 ({CO}_{2})$ in above reaction.

$∴$ $(C_{2} O_{4}^{2 -})$ acts as a reductant.

⇒Redox Reaction