Redox Reactions

A compound in which a metal ion M^x+ (Z = 25) has a spin only magnetic moment of $\sqrt{24}$ BM. The number of unpaired electrons in the compound and the oxidation state of the metal ion are respectively

• 4 and 2

• 5 and 3

• 3 and 2

• 4 and 3

MnO^-₄  ions are reduced in acidic condition to Mn²⁺ ions whereas they are reduced in neutral condition to MnO₂. The oxidation of 25 mL of a solution X containing Fe²⁺ ions required in acidic condition 20 mL of a solution Y containing MnO^-₄ ions. What volume of solution Y would be required to oxidise 25 mL of a solution X containing Fe²⁺ ions in neutral condition? 

• 11.4 mL

• 12.0 mL

• 33.3 mL

• 35.0 mL

Which one of the following reactions involves disproportionation?

• 2H₂SO₄ + Cu → CuSO₄ + 2H₂O + SO₂

• As₂O₃ + 3H₂S → As₂S₃ + 3H₂O

• 2KOH + Cl₂ → KCl KOCl + H₂O

• 4NH₃ + 3O₂ → 2N₂ + 6H₂O

aK₂Cr₂O₇ + bHCl + cH₂SO₄ → xCrO₂Cl₂ + yKHSO₄ + zH₂O.

The above equation balances when:

• a = 2; b = 4; c = 6 and x = 2; y = 6; z = 3

• a = 4; b = 2; c = 6 and x = 6; y = 2; z = 3

• a = 6; b = 4; c = 2 and x = 6; y = 3; z = 2

• a = 1; b = 4; c = 6 and x = 2; y = 6; z = 3

In one of the following reactions HNO₃ does not behave as an oxidizing agent. Identify it :

• 2HNO₃ + P₂O₅ → 2HPO₃ + N₂O₅

• I₂ + 10 HNO₃ → 2HIO₃ + 10 NO₂ + 4H₂O

• 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O

• NO₃ + 3Fe²⁺ + 4H⁺ → NO + 3Fe³⁺ + 2H₂O

In which of the following reactions, H₂O₂ acts as a reducing reagent?

• PbO₂(s) + H₂O(aq) → PbO(s) + H₂O(l) +  O₂(g)

• Na₂SO₃(aq) + H₂O₂(aq) → Na₂SO₄(aq) + H₂O(l)

• 2KI(aq) + H₂O₂(aq) → 2KOH(aq) + I₂(s)

• KNO₂(aq) + H₂O₂(aq) → KNO₃(aq) + H₂O(l)

In organic reactions, sodium in liquid ammonia is used as

• reducing agent

• hydrating agent

• oxidising agent

• precipitating agent

What are the oxidation numbers of nitrogen in NH₄NO₃ ?

• +3, -5

• -3, +5

• +3, -6

• +2, +2

In which of the following reactions, chlorine acts as an oxidising agent?

(i) CH₃CH₂OH + Cl₂ → CH₃CHO + HCl

(ii) CH₃CHO + Cl₂ → CCl₃ . CHO + HCl

(iii) CH₄ + Cl₂ $\stackrel{\mathrm{hv}}{\to }$ CH₃Cl + HCl

The correct answer is-

• (i) only

• (ii) only

• (i) and (iii)

• (i), (ii) and (iii)

Which one of the following is an example of disproportionation reaction?

• 3Cl₂ (g) + 6OH^- (aq) → ClO${}_3^{-}$ (aq) + 5Cl^- (aq) + 3H₂O (l)

• Ag²⁺ (aq) + Ag (s) → 2Ag⁺ (aq)

• Zn (s) + CuSO₄ (aq) → Cu (s) + ZnSO₄ (aq)

• 2KClO₃ (s) → 2KCl (s) + 3O₂ (g)