Practice Paper 3 (F/M/22/23)

Which statement about graphite explains why it is used as an electrode?

• It contains ions.

• It has a giant covalent structure.

• It is a metal.

• It has mobile electrons.

Magnesium powder reacts with an excess of dilute hydrochloric acid to produce hydrogen gas. Which statements about this reaction are correct?

• The smaller the particles of magnesium powder, the more slowly the hydrogen is

  produced.

• The higher the temperature, the faster the magnesium powder disappears.

• The lower the concentration of dilute hydrochloric acid, the faster the rate of

  reaction.

• The faster the magnesium powder disappears, the faster the rate of reaction.

The reaction between two aqueous compounds, X and Y, is slow and exothermic. The graph shows how the rate of this reaction changes with time. Which suggestions given by a student is/are correct why the rate of reaction decreases with time?

• the activation energy decreases

• the speed of the molecules of X and Y decreases

• the concentration of both X and Y decreases with time.

Hydrogen reacts with iodine to form hydrogen iodide.

H₂(g) + I₂(g) → 2HI(g)

Which statements explain why the reaction is faster when the pressure is increased, at constant temperature?

• At higher pressure, the molecules are moving faster.

• At higher pressure, more of the molecules have the required activation energy.

• At higher pressure, the molecules are closer together.

• At higher pressure, the molecules collide more frequently.

The structure of organic compound X is shown. What is X?

• ethyl ethanoate

• ethyl methanoate

• methyl ethanoate

• methyl methanoate

Substance M is a solid at 30^oC. The substance is heated to 80^oC, and its temperature measured as it cools down to room temperature. The cooling curve is shown. Between which times is substance M freezing?

• P to Q

• Q to R

• R to S

• S to T

Part of the Periodic Table is shown. Which element has two electrons in its outer shell and three electron shells?

• A

• B

• C

• D

Copper(II) sulfate is prepared by adding excess copper(II) carbonate to sulfuric acid. Why is an excess of copper(II) carbonate added?

• to ensure all the copper(II) carbonate has reacted

• to ensure all the sulfuric acid has reacted

• to increase the rate of reaction

• to increase the amount of copper(II) sulfate produced

Concentrated aqueous copper(II) sulfate is electrolysed using copper electrodes. Which ionic half-equation describes the reaction taking place at the cathode?

• 2H⁺ + 2e^- → H₂

• 4OH^- → O₂ + 2H₂O + 4e^-

• Cu → Cu²⁺ + 2e^-

• Cu²⁺ + 2e^- → Cu

An aqueous solution reacts with a solid. The products are an alkaline gas, a salt and water. What are the aqueous solution and the solid?

• sodium hydroxide solution and magnesium carbonate

• hydrochloric acid solution and magnesium carbonate

• hydrochloric acid solution and ammonium chloride

• sodium hydroxide solution and ammonium chloride