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Redox Reactions

Multiple Choice Questions

81.

Balance the following equation by chossing the correct options:

xKNO₃ + yC₁₂H₂₂O₁₁ → pN₂ + qCO₂ + rH₂O + sK₂CO₃

x y p q r s

36 55 24 24 5 48
x y p q r s

48 5 24 36 55 24
x y p q r s

24 24 55 48 5
x y p q r s

24 48 36 24 5 55

82.

(I)H₂O₂ +O₃ --> H₂O +2O₂
(II) H₂O₂ +Ag₂O +--> 2Ag +H₂O +O₂
Role of hydrogen peroxide in the above reaction is respectively

oxidising in (I) and reducing (II)
reducing (I) and oxidizing in (II)
reducing in (I) and (II)
reducing in (I) and (II)

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83.

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

zero to +1 and zero to -5
zero to -1 and zero to +5
zero to -1 and zero to +5
zero to -1 and zero to +5

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84.

In which of the following compounds, nitrogen exhibits highest oxidation state?

N₂H₄
NH₃
N₃H
N₃H

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85.

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

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86.
For the redox reaction
$M n O_{4}^{-} + C_{2} O_{4}^{- 2} + H^{+} \overset{}{\to} M n^{2 +} + C O_{2} + H_{2} O$
The correct coefficients of the reactants for the balanced equation are

$M n O_{4}^{-}$ $C_{2} O_{4}^{2 -}$ H⁺

16 5 2

MnO₄^- C₂O₄^2- H⁺

2 5 16

MnO₄^- C₂O₄^2- H⁺

5 16 2

MnO₄^- C₂O₄^2- H⁺

2 16 5

MnO₄^-	C₂O₄^2-	H⁺
2	5	16

$\overset{+ 7}{M n} O_{4}^{-} \overset{}{\to} \overset{+ 2}{M} n^{2 +}; 5 e^{-} g a i n . . . (i) {\overset{+ 3}{C}}_{2} O_{4}^{2 -} \overset{}{\to} \overset{+ 4}{C} O_{2}; 2 e^{-} l o s s . . . (i i) M u l t i p l y i n g (i) a n d 2 a n d (i i) b y 5 t o b a l a n c e e^{-} 2 M n O_{4}^{-} + 5 C_{2} O_{4}^{2 -} \overset{}{\to} 2 M n^{2 +} + 10 C O_{2} O n b a l a n c i n g c h a r g e; 2 M n O_{4}^{-} + 5 C_{2} O_{4}^{2 -} + 16 H^{+} \overset{}{\to} 2 M n^{2 +} + 10 C O_{2} + 8 H_{2} O$

87.

when I^- is oxidised by MnO₄^- in an alkaline medium I^- converts into

IO₃^-
I₂
IO₄^-
IO^-

88.

For the formation of Cr₂O₃ and Al₂O₃, values of $∆_{f} G °$ are 540 kJ mol^-1 and -827 kJ mol^-1 respectively. What will be the possibility for reaction of Cr₂O₃ by Al?