Chemical Changes questions

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Chemical Changes question collection

Review Chemical Changes questions for Chemistry, with correct answers shown and coverage across acids, alkalis and neutralisation; reactivity series and displacement; electrolysis.

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Question 1

Which metal is least reactive in this list?
  1. Gold
  2. Magnesium
  3. Aluminium
  4. Zinc

Question 2

In the reaction CuO + H2 → Cu + H2O, which substance is reduced?
  1. Copper oxide
  2. Hydrogen
  3. Copper
  4. Water

Question 3

What happens to an element's oxidation state during oxidation?
  1. It increases
  2. It decreases
  3. It stays unchanged
  4. It becomes zero

Question 4

What are the products when hydrochloric acid reacts with magnesium?
  1. Magnesium chloride and hydrogen
  2. Magnesium chloride and oxygen
  3. Magnesium oxide and water
  4. Magnesium hydroxide

Question 5

What are the products of an acid-carbonate reaction?
  1. Salt + water + carbon dioxide
  2. Salt + hydrogen
  3. Salt + oxygen + water
  4. Salt + alkali

Question 6

Which ionic equation represents neutralisation?
  1. \(\mathrm{H}^{+} + \mathrm{OH}^{-} \to \mathrm{H}_{2}\mathrm{O}\)
  2. \(\mathrm{H}^{+} + \mathrm{Cl}^{-} \to \mathrm{HCl}\)
  3. \(\mathrm{Na}^{+} + \mathrm{OH}^{-} \to \mathrm{NaOH}\)
  4. \(2\mathrm{H}^{+} + \mathrm{O}^{2-} \to \mathrm{H}_{2}\)

Question 7

Which method is used to make pure, dry copper sulfate from copper oxide and sulfuric acid?
  1. Add excess copper oxide, filter, then crystallise the filtrate
  2. Add exact amounts and evaporate to dryness directly
  3. Add copper oxide and distil off sulfuric acid
  4. Use titration with no filtration needed

Question 8

In electrolysis, reduction happens at the?
  1. Cathode
  2. Anode
  3. Electrolyte
  4. External circuit

Question 9

In electrolysis, oxidation happens at the?
  1. Anode
  2. Cathode
  3. Power supply
  4. Salt bridge

Question 10

What forms at the cathode during electrolysis of molten lead bromide (PbBr2)?
  1. Lead
  2. Bromine
  3. Oxygen
  4. Hydrogen

Question 11

During electrolysis of aqueous sodium chloride (brine), what forms at the cathode?
  1. Hydrogen gas
  2. Sodium metal
  3. Chlorine gas
  4. Oxygen gas

Question 12

During electrolysis of aqueous sodium chloride (brine), what forms at the anode?
  1. Chlorine gas
  2. Hydrogen gas
  3. Sodium metal
  4. Water vapour

Question 13

Which metal can displace copper from copper sulfate solution?
  1. Iron
  2. Silver
  3. Gold
  4. Platinum

Question 14

What does a lower pH mean for an acid solution?
  1. Higher \(\mathrm{H^+}\) concentration
  2. Lower \(\mathrm{H^+}\) concentration
  3. Higher \(\mathrm{OH^-}\) concentration
  4. Lower total ion concentration

Question 15

Which property makes a strong acid produce more \(\mathrm{H^+}\) than a weak acid?
  1. More complete ionisation
  2. More hydrogen atoms per molecule
  3. Lower relative formula mass
  4. Higher boiling point

Question 16

Which quantity does a titration determine precisely?
  1. Neutralising volume
  2. Reaction temperature change
  3. Gas volume
  4. Rate from mass loss

Question 17

In electroplating with copper, the object to be plated is the?
  1. Cathode
  2. Anode
  3. Electrolyte
  4. Power supply

Question 18

What is the correct half equation for Al3+ ions at the cathode?
  1. \(\mathrm{Al}^{3+} + 3\mathrm{e}^{-} \to \mathrm{Al}\)
  2. \(\mathrm{Al} \to \mathrm{Al}^{3+} + 3\mathrm{e}^{-}\)
  3. \(\mathrm{Al}^{3+} \to \mathrm{Al} + 3\mathrm{e}^{-}\)
  4. \(\mathrm{Al} + 3\mathrm{e}^{-} \to \mathrm{Al}^{3+}\)

Question 19

Which equation shows reduction of copper(II) oxide by carbon?
  1. \(2\mathrm{CuO} + \mathrm{C} \to 2\mathrm{Cu} + \mathrm{CO}_{2}\)
  2. \(\mathrm{Cu} + \mathrm{CO}_{2} \to \mathrm{CuO} + \mathrm{C}\)
  3. \(2\mathrm{Cu} + \mathrm{O}_{2} \to 2\mathrm{CuO}\)
  4. \(\mathrm{CuO} + \mathrm{H}_{2}\mathrm{O} \to \mathrm{Cu(OH)}_{2}\)

Question 20

What is oxidation in terms of electrons?
  1. Loss of electrons
  2. Gain of electrons
  3. Gain of protons
  4. Loss of neutrons

Question 21

What is reduction in terms of electrons?
  1. Gain of electrons
  2. Loss of electrons
  3. Gain of neutrons
  4. Loss of atoms

Question 22

What is electrolysis?
  1. Decomposing an ionic compound with electricity
  2. Generating electricity from a chemical reaction
  3. Separating dissolved solids by filtration
  4. Dissolving electrodes without a current

Question 23

What happens to negative ions at the positive electrode?
  1. Negative ions lose electrons
  2. Negative ions gain electrons
  3. Positive ions lose electrons
  4. Positive ions gain electrons

Question 24

What does the reactivity series predict?
  1. Whether one metal displaces another
  2. Metal melting-point order
  3. Metal density order
  4. Metal conductivity order

Question 25

Which aluminium property means it needs electrolysis for extraction?
  1. More reactive than carbon
  2. Low density
  3. Good electrical conductor
  4. Protective oxide layer

Question 26

Which acid ion is replaced when a salt forms?
  1. Hydrogen ions
  2. Hydroxide ions
  3. Oxide ions
  4. Metal ions

Question 27

Which apparatus delivers a measured variable volume in a titration?
  1. Burette
  2. Volumetric pipette
  3. Volumetric flask
  4. Measuring cylinder

Question 28

What is formed when a metal reacts with oxygen?
  1. A metal oxide
  2. A metal hydroxide
  3. A metal chloride
  4. A metal carbonate

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Review Chemical Changes questions for Chemistry, with correct answers shown and coverage across acids, alkalis and neutralisation; reactivity series and displacement; electrolysis.

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