REdox G9

Which of the following statements refers to an oxidation process?

• Hydrogen is added to ethene

• Oxygen is removed from carbon dioxide

• Chlorine accepts electrons

• Increase in the oxidation number of magnesium metal

Which of these equations represents a redox reaction?

• Ca(HCO₃)_{2 -->} CaCO₃ + H₂O + CO₂

• CH₃COOH + NaOH --> CH₃COONa + H₂O

• Zn + 2FeCl₃ --> ZnCl₂ + 2FeCl₂

• NaCl + AgNO_{3 -->} AgCl + NaNO₃

What is the oxidation number of chlorine in ClO₃^- ?

• -1

• +1

• -1

• +5

What are the oxidation numbers of manganese in the manganese compounds shown below?

• A

• B

• C

• D

Which of the following is the oxidising agent in the experiment shown the diagram?

• Iron(II) ion

• Sulphate ion

• Iron

• Bromine

Which of the following statements is not true when zinc powder is added to dilute hydrochloric acid?

• Zinc is oxidised

• Chloride ion acts as an oxidising agent

• Hydrogen ion is reduced

• Electrons are transferred in the reaction

The table shows four chemical changes. Which changes involve donation of electrons?

• P and Q

  P and R

  Q and S

  R and S

• P and R

• Q and S

• R and S

The diagram shows two metals P and Q connected together in a liquid jelly. Metal Q is more electropositive than metal P. Which of the following statements is true?

• P is oxidised

• Q is reduced

• The oxidation number of metal P has increased

• The oxidation number of metal Q has increased

A mixture of magnesium oxide, copper(II) oxide and zinc powder is heated in a crucible until no further changes are observed. After heating, the mixture contains:

• magnesium, copper(II) oxide and zinc

• magnesium oxide, copper and zinc oxide

• magnesium oxide, copper(II) oxide and zinc

• magnesium, copper and zinc oxide

In an electrochemical cell, tin becomes a negative terminal when it is connected to

• aluminium

• lead

• magnesium

• zinc