O level Chemistry Redox (10 qns)

In which reaction does the ocidation state of iron remain unchanged?

• 2 FeCl₂ + Cl₂ → 2FeCl₃

• 2 FeCl₂ + Mg → MgCl₂ +Fe

• Fe + 2 FeCl₃ → 3 FeCl₂

• Fe₂O₃ + 6 HCl → 2 FeCl₃ + 3 H₂O

The equation shows the reaction between copper(II) oxide and carbon. What is the function of the copper (II) oxide in the reaction?

• catalyst

• oxidising agent

• reducing agent

• dehydrating agent

Which reaction does not involve either oxidation or reduction?

• CH₄ (g) + 2O₂ (g) → CO₂ (g) + 2 H₂O (g)

• Cu²⁺ (aq) + Zn (s) → Cu (s) Zn²⁺ (aq)

• CuO (s) + H₂SO₄ (aq) → CuSO₄ (aq) + H₂O (l)

• Zn (s) + H₂SO₄ (aq) → ZnSO₄ (aq) + H₂ (g)

Which of the following is a redox reaction?

• NH₃ + H⁺ → NH₄⁺

• N₂ + 3H₂ → 2 NH₃

• NH₄⁺ + Cl^- → NH4Cl

• NH₄⁺ + OH^- → NH₄OH

The diagram shows an experimental set up used to reduce substance V. Which of the following pairs could be U and V?

• U: copper

  V: copper(II) oxide

• U: copper

  V: lead(II) oxide

• U: lead

  V: lead(II) oxide

• U: magnesium

  V: copper(II) oxide

Crysotile, Mg₃Si₂O₅(OH)₄ is an asbestos mineral. What is the oxidation state of silicon in the mineral?

• - 4

• - 2

• + 2

• + 4

After adding acidified potassium manganate (VII) solution to a cample of solution X, the potassium manganate (VII) solution was decolourised and the resulting solution was brown. When starch solution was added to a fresh sample of solution X, the solution turned dark blue. What conclusion can be drawn about solution X?

• It is a reducing agent and it contains ioodide ions

• It is a reducing agent and it contains bromide ions

• It is a oxidising agent and it contains ioodide ions

• It is a oxidising agent and it contains bromide ions

In which stages is silicon reduced?

• I only

• I and II only

• I and IV only

• II and III only

Which reaction does not involve oxidation and/or reduction?

• Cl₂ + 2 Br^- → 2 Cl^- + Br₂

• Ag⁺ + Cl^- →AgCl

• Mg + 2 HCl → MgCl₂ + H₂

• 2 Na + Cl₂ → 2 NaCl

The propellant used in the solid rocket booster of a space shuttle is a mixture of aluminium and compound P.

Compound P contains chlorine with an oxidation state of +7. Which of the following could be compound P?

• NCl₃

• NH₄Cl

• NH₄ClO₃

• NH₄ClO₄