(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)

• oxidising in (I) and (II)

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?

• S

• H

• Cl

• C

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

• N₂H₄

• NH₃

• N₃H

• NH₂OH

C.

N₃H

Thus, oxidation state of nitrogen is highest in N₃H_.

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 -3

For the redox reaction

$Mn{O}_4^{-} + C_2{O}_4^{-2} + H^{+} \stackrel{ }{\to } M{n}^{2+} + C{O}_2 + H_{2}O$

The correct coefficients of the reactants for the balanced equation are

• $Mn{O}_4^{-}$	$C_2{O}_4^{2-}$	H+
  16	5	2

• MnO4-	C2O42-	H+
  2	5	16

• MnO4-	C2O42-	H+
  5	16	2

• MnO4-	C2O42-	H+
  2	16	5