Redox Reaction and Method for Balancing Redox Reaction MCQs

Balancing redox reactions can be quite complex, so a systematic approach is essential. The half-reaction method for balancing redox reactions highlights that redox reactions can be divided into two separate processes: an oxidation half-reaction, which shows only the oxidation process, and a reduction half-reaction, which shows only the reduction process. To achieve an overall balanced reaction, the two half-reactions are combined so that the electrons in each half-reaction cancel out. This method is particularly useful for reactions occurring in aqueous solutions. By combining the two half-reactions, a balanced redox equation is obtained.

Zn gives H2 gas with H2SO4 and HCl but not with HNO3 because

(a) Zn acts as an oxidising agent when it reacts with HNO3
(b) HNO3 is a weaker acid than H2SO4 and HCl
(c) In electrochemical series, Zn is above hydrogen
(d) NO3– is reduced in preference to hydronium ion

One mole of N2H4 loses 10 moles of electrons to form a new compound y. Assuming that all nitrogen appears in the new compound, what is the oxidation state of nitrogen in y.

(a) -1
(b) -3
(c) +3
(d) +5

Which of the following represents a redox reaction?

(a) NaOH + HCl → NaCl + H2O
(b) BaCl2 + H2SO4 → BaSO4 + 2HCl
(c) CuSO4 + 2H2O → Cu(OH)2 + H2SO3
(d) Zn + 2HCl → ZnCl2 + H2

In the reaction

3Br2 + 6CO32- + 3H2O → 5Br– + BrO3– + 6HCO3–

(a) bromine is oxidised and carbonate is reduced
(b) bromine is reduced and water is oxidised
(c) bromine is neither reduced nor oxidised
(d) bromine is both reduced and oxidised

A solution contains Fe2+, Fe3+ and I– ions. This solution was treated with iodine at 35°C. Eo for Fe3+/Fe2+ is 0.77V and Eo for I2/2I– = 0.536V. The favourable redox reaction is

(a) I2 will be reduced to I–
(b) there will be no redox reaction
(c) I– will be oxidised to I2
(d) Fe2+ will be oxidised to Fe3+

Which reaction involves neither oxidation nor reduction?

(a) CrO42- -→ Cr2O72-
(b) Cr → CrCl3
(c) Na → Na+
(d) 2S2O32- → S4O62-

The oxidation number of Pt in [Pt(C2H4)Cl3]– is

(a) +1
(b) +2
(c) +3
(d) +4

Which of the following cannot function as an oxidising agent?

(a) I–
(b) Si(s)
(c) NO3–(aq)
(d) Cr2O72-

The equivalent mass of oxidising agent in the following reaction is

SO2 + 2H2S → 3S + 2H2O

(a) 32
(b) 64
(c) 16
(d) 8

A compound of Xe and F is found to have 53.5% of Xe. What is the oxidation number of Xe in this compound?

(a) -4
(b) 0
(c) +4
(d) +6