Electrochemistry Form 4

Which of the following is true about an electrolyte?

I Electrolyte conducts electricity in molten state.

II Electrolyte conducts electricity in solid state.

III Electrolyte is soluble in water.

IV Electrolyte undergoes chemical decomposition when it conducts electricity.

• I and II only

• II and III only

• II and IV only

• I and IV only

Which of the following is not an electrolyte?

• Molten glucose

• Aqueous ammonia

• Molten lead (II) bromide

• Molten potassium iodide

Naphthalene does not conduct electricity because it

• contains freely moving electrons.

• has very low melting points.

• consists of molecules which are uncharged particles.

• contains ionic compounds which can dissolve in water.

Which of the following is most probably substance X?

• Molten napthalene

• Pure ethanol

• Solid lead (II) bromide

• Potassium iodide solution

What are the ions present in molten lead (II) bromide?

• PbBr₂

• Pb and Br

• Pb²⁺ and Br^–

• Pb²⁺ and Br₂^–

Which of the following happens during the electrolysis of molten sodium bromide?

I Sodium ions are attracted to the cathode.

II Bromide ions are attracted to the anode.

III Electrons are moving from anode to cathode.

IV At the cathode, bromine ions accept electron from anode.

• I, II and III only

• I, II and IV only

• I, III and IV only

• II, III and IV only

What is formed at carbon electrode Q?

• Hydrogen gas

• Oxygen gas

• Iron metal

• Nitrogen gas

The electrolysis of aqueous sodium nitrate using carbon electrode was carried out in a lab. Which of the following is true about this experiment?

• The sodium ions are discharged at the cathode.

• The nitrate ions are discharged at the anode.

• Hydrogen gas is produced in the anode

• Oxygen gas is produced in the anode.

What need to be changed in order to get different gas from this experiment?

• Substitute carbon electrodes with copper electrodes.

• Use a more concentrated copper (II) chloride solution.

• Change the position of the battery.

• Substitute carbon electrodes with platinum.

Which of the following are the factors that determine the type of ions to be discharged at the electrodes?

I Type of electrode used.

II Concentration of ions in the solution.

III The molecular mass of the atom used.

IV Position of ions in electrochemical series.

• I, II and III only

• I, II and IV only

• I, III and IV only

• II, III and IV only