Redox Quiz

Which of the following is involved in reduction?

• Loss of oxygen

• Loss of hydrogen

• Loss of electrons

• Increase in oxidation state

Which conversion is an example of oxidation?

• Copper(II) oxide to copper

• Copper(II) oxide to copper(II) sulfate

• Magnesium to magnesium oxide

• Iron(III) oxide to iron(II) oxide

A reducing agent __________.

• removes hydrogen

• is reduced at the end of a reaction

• gains oxygen

• accepts electrons

In the reaction, Fe₂O₃(s)  +  3CO(g)  →  2Fe(l)  +  3CO₂(g), _________.

• carbon monoxide is reduced

• carbon monoxide is the oxidising agent

• iron(III) oxide is oxidised

• iron(III) oxide is the oxidising agent

Which reaction is a redox reaction?

• Sodium hydroxide  +  hydrochloric acid  →  sodium chloride  +  water

• Potassium bromide  +  chlorine  →  potassium chloride  +  bromine

• Barium chloride  +  zinc sulfate  →  barium sulfate  +  zinc chloride

• Silver nitrate  +  sodium chloride  →  silver chloride  +  sodium nitrate

Substance X changes aqueous potassium iodide from colourless to brown and changes aqueous potassium manganate(VII) from purple to colourless. Which of the following correctly describes X?

• It is an oxidising agent only.

• It is a reducing agent only.

• It is an oxidising agent and a reducing agent.

• It is neither an oxidising agent nor a reducing agent.

Hydrogen peroxide reacts with iodide ions as follows: 

H₂O₂(l)  +  2I^-(aq)  + 2H⁺(aq)→  2H₂O(l) +  I₂(aq)

In this reaction, the hydrogen peroxide is acting as _____________.

• a catalyst

• an oxidising agent

• a reducing agent

• both an oxidising and reducing agent

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

• FeSO₄(aq)  +  2NaOH(aq)  →  Fe(OH)₂(s)  +  Na₂SO₄(aq)

• 2Fe(s)  +  3Cl₂(g)  →  2FeCl₃(s)

• Fe₂O₃(s)  +  3CO(g)  →  2Fe(l)  +  3CO₂(g)

• Fe(s)  +  2HCl(aq)  →  FeCl₂(aq)  +  H₂(g)

Which of these are good reducing agents?

   

1)       Potassium manganate(VII)

2)       Potassium iodide

3)       Sodium metal

4)       Bromine

• 1, 2 and 3

• 1, 3 and 4

• 2 and 3

• 3 and 4

Polluted air with sulfur dioxide gas is bubbled through acidified potassium manganate (VII) and aqueous potassium iodide separately. Which of the following shows the correct colours observed in the respective solutions?

• A

• B

• C

• D