ES Multiple Choice Questions

Question 1

Which equation correctly shows the first ionisation enthalpy of bromine?

• Br_2(aq) + 2e^– –> 2Br^–_(aq)
• Br_(g) + e^– –> Br^–_(g)
• Br_(g) –> Br⁺_(g) + e^–
• Br_(l) –> Br⁺_(g) + e^–

Answer 1

• Br_(g) –> Br⁺_(g) + e^–

Question 2

Which of these properties decreases down Group 17?

• The atomic radius of the halogen atoms.
• The oxidising power of the halogen elements.
• The reducing power of the halide ions.
• The boiling point of the elements.

Answer 2

• The oxidising power of the halogen elements.

Question 3

What is the oxidation number of sulfur in Na₂S₄O₆?

• -1
• +1.5
• +2.5
• +6

Answer 3

• +2.5

Question 4

Aqueous solutions of four salts are electrolysed.

For the solution of which salt would you expect to observe a gas formed at the cathode?

• copper(II) chloride
• copper(II) iodide
• potassium nitrate
• silver nitrate

Answer 4

• potassium nitrate

Question 5

Fermentation is used to make ethanol. The equation for the reaction is given below, along with the Mr values for each molecule.

C₆H₁₂O_6(aq) –> 2C₂H₆O_(aq) + 2CO_2(g)

Mr of C₆H₁₂O_6(aq): 180
Mr of C₂H₆O_(aq): 46
Mr of CO_2(g): 44

Answer 5

• B

Question 6

Which change would move the position of the following equilibrium towards the right?

I_2(aq) + 2OH^–_(aq) ⇌ I^–_(aq) + IO^–_(aq) + H₂O_(l)

• Adding solid potassium hydroxide and stirring to dissolve it.
• Adding solid potassium iodide and stirring to dissolve it.
• Adding sulfuric acid.
• Increasing the pressure.

Answer 6

• Adding solid potassium hydroxide and stirring to dissolve it.

Question 7

Which change in conditions would result in an increase in the concentration of HClO produced in the following reaction?

Cl_2(aq) + H2O_(l) ⇌ HCl_(aq) + HClO_(aq) ΔH = negative

• Decreasing the temperature.
• Increasing the temperature.
• Adding hydrochloric acid.
• Using a catalyst.

Answer 7

• Decreasing the temperature.

Question 8

When nitrogen dioxide is produced in a sealed syringe and allowed to stand, it eventually forms an equilibrium mixture with dinitrogen tetroxide:

2NO_2(g) (BROWN GAS) ⇌ N₂O_4(g) (COLOURLESS GAS)

As the mixture moves towards equilibrium, which statement is true?

• The N₂O₄ molecules don’t decompose into NO₂.
• The volume of the gas mixture increases.
• The forward reaction rate exceeds the reverse reaction rate.
• The brown colour gets darker.

Answer 8

• The forward reaction rate exceeds the reverse reaction rate.

Question 9

The concentration of iodine present in a mixture can be determined by titration with sodium thiosulfate, according to the following equation:

I₂ + 2Na₂S₂O₃ –> 2NaI + Na₂S₄O₆

Which statement is true for this titration?

• The iodine acts as a reducing agent.
• The mixture turns from colourless to brown.
• The ratio between oxygen and sulfur stays the same, so the oxidation state of the sulfur doesn’t change.
• The titration can be used to indirectly determine the concentration of chlorine in swimming pool water.

Answer 9

• The titration can be used to indirectly determine the concentration of chlorine in swimming pool water.

Question 10

Which of the following statements is/are true of the sulfur compounds formed when solid potassium bromide is reacted with concentrated sulfuric acid?

1. Potassium hydrogen sulfate is formed.
2. Sulfur dioxide is formed.
3. Hydrogen sulfide is formed.

• 1,2, and 3
• Only 1 and 2
• Only 2 and 3
• Only 1

Answer 10

• Only 1 and 2