O LevelChemistryCambridge (CIE)Exam Questions3. Stoichiometry3.1 Formulae

Formulae (Cambridge (CIE) O Level Chemistry): Exam Questions

Exam code: 5070

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3.1 Formulae

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1
1 mark

A molecule contains carbon, hydrogen and oxygen. For every carbon atom there are twice as many hydrogen atoms but the same number of oxygen atoms.

What is the formula of the molecule?

  • C2H6O

  • C2H4O2

  • C4H8O2

  • C2H2O2

Choose your answer

2
1 mark

Theobromine is a stimulant found in chocolate and in tea leaves and is closely related to caffeine, the stimulant found in coffee.

q2-2-4-mcq-easy-cie-igcse-che

What is the formula of theobromine?

  • C6H5N4O2

  • C7H8N4O2

  • C7H8N3O2

  • C7H7N4O2

Choose your answer

3
1 mark

Hydrogen reacts with elements from Group VII to produce compounds called hydrogen halides. An example is when a molecule of hydrogen reacts with a molecule of fluorine to produce hydrogen fluoride.

What is the correct equation for the reaction?

  • 2 H + 2 F → 2 HF

  • H2 + F2 → H2F2

  • 2 H + 2 F → H2F2

  • H2 + F2 → 2 HF

Choose your answer

4
1 mark

Aluminium ions have the formula Al3+ and chloride ions have the formula Cl-.

What is the formula of aluminium chloride?

  • AlCl

  • Al3Cl

  • AlCl3

  • (Al3+)(Cl-)3

Choose your answer

5
1 mark

The diagram shows a model of one molecule of a compound.

Figure 1

A central grey circle joined by straight lines to four black circles arranged around it. Two of the black circles are each joined by a further short line to a smaller white circle. Below a horizontal rule, a key shows a white circle labelled hydrogen, a grey circle labelled sulfur and a black circle labelled oxygen.

What is the formula of the compound?

  • HSO4

  • H2SO3

  • H2SO4

  • H2S4O

Choose your answer

1
1 mark

What is the balanced equation for the reaction of methane and oxygen?

  • CH4(g) + 2 O2(g) → CO2(g) + H2O(g)

  • CH4(g) + O2(g) → CO2(g) + 2 H2O(g)

  • 2 CH4(g) + 4 O2(g) → 2 CO2(g) + H2O(g)

  • CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)

Choose your answer

2
1 mark

A compound contains two atoms of oxygen and one atom of calcium. It also contains hydrogen in sufficient amounts so that the overall charge of the molecule is neutral.

What is the molecular formula for the compound?

  • Ca(OH)4

  • Ca(OH)2

  • H4CaO2

  • CaO2H2

Choose your answer

3
1 mark

Dilute sulfuric acid and barium chloride solution react to produce barium sulfate and hydrochloric acid, as shown in the reaction below:

H2SO4 + BaCl2 → BaSO4 + 2 HCl

Which row represents the correct state symbols for the reaction?

 

H2SO4

BaCl2

BaSO4

HCl

A

(aq)

(l)

(s)

(aq)

B

(l)

(aq)

(aq)

(l)

C

(aq)

(aq)

(s)

(aq)

D

(l)

(aq)

(aq)

(l)

    Choose your answer

    4
    1 mark

    The formula and charge for positive and negative ions are shown.

    cation

    anion

    Al3+, Mg2+, Cu2+, Fe2+, Li+

    F-, CO32-, NO3-, S2-, SO42-

    The table shows the name and formula of common ionic compounds formed from the ions. Which row is not correct?

     

    name

    formula

    A

    lithium sulfide

    Li2S

    B

    iron(II) fluoride

    Fe2F3

    C

    aluminium sulfate

    Al2(SO4)3

    D

    magnesium nitrate

    Mg(NO3)2

      Choose your answer

      5
      1 mark

      How many elements combine to form the compound ammonium sulfate?

      • 2

      • 4

      • 10

      • 15

      Choose your answer

      6
      1 mark

      The equation for the reaction between ethyne, C2H2, and oxygen is shown.

      2C2H2(g) + xO2(g) → yCO2(g) + zH2O(g)

      When the equation is balanced, what is x?

      • 2

      • 3

      • 4

      • 5

      Choose your answer

      7
      1 mark

      Calcium phosphate is used as a source of phosphorus in fertilisers. It contains Ca2+ ions and PO43- ions.

      What is the formula of calcium phosphate?

      • CaPO4

      • Ca2(PO4)3

      • Ca3(PO4)2

      • Ca3PO8

      Choose your answer

      1
      1 mark

      The left hand side for the reaction between ammonia and copper(II) oxide is shown. What are the products of the balanced equation?

      3 CuO + 2 NH3 →

      • 3 Cu + 2 N + 3 H2O

      • 3 Cu + 3 HNO3

      • 3 Cu + N2 + H2O

      • 3 Cu + N2 + 3 H2O

      Choose your answer

      2
      1 mark

      What is the balanced equation for the reaction between aqueous NaOH and Fe2(SO4)3?

      • Fe2(SO4)3 (aq) + 6 NaOH (aq) → 2 Fe(OH)3 (s) + 3 Na2SO4 (aq)

      • Fe2(SO4)3 (aq) + 2 NaOH (aq) → Fe(OH)3 (s) + Na2SO4 (aq)

      • 2 Fe2(SO4)3 (aq) + 4 NaOH (aq) → Fe(OH)3 (s) + Na2SO4 (aq)

      • 3 Fe2(SO4)3 (aq) + 6 NaOH (aq) → 3 Fe(OH)3 (s) + 2 Na2SO4 (aq)

      Choose your answer

      3
      1 mark

      Magnesium nitrate and sodium carbonate react as shown.

      Mg(NO3)2 (aq) + Na2CO3 (aq) → MgCO3 (s) + 2 NaNO3 (aq)

      Which row describes the spectator ions and the net ionic equation for the reaction?

      spectator ions

      net ionic equation

      A

      Mg2+ and CO32-

      Mg2+ (aq) + CO32- (aq) → MgCO3 (s)

      B

      NO3- and Na+

      NO3- (aq) + Na+ (aq) → NaNO3 (aq)

      C

      Mg2+ and CO32-

      NO3- (aq) + Na+ (aq) → NaNO3 (aq)

      D

      NO3- and Na+

      Mg2+ (aq) + CO32- (aq) → MgCO3 (s)

        Choose your answer

        4
        1 mark

        Nitric acid and potassium hydroxide react in a neutralisation reaction to produce a salt and water, as shown by the equation below:

        HNO3 (aq) + KOH (aq) → KNO3 (aq) + H2O (l)

        Which row describes the spectator ions and the net ionic equation for the reaction?

        spectator ions

        net ionic equation

        A

        NO3- and K+

        NO3- (aq) + K+ (aq) → KNO3 (aq)

        B

        H+ and OH-

        NO3- (aq) + K+ (aq) → KNO3 (aq)

        C

        NO3- and K+

        H+ (aq) + OH- (aq) → H2O (l)

        D

        H+ and OH-

        H+ (aq) + OH- (aq) → H2O (l)

          Choose your answer

          5
          1 mark

          For which substance is the formula shown an empirical formula but not a molecular formula?

          • sodium chloride, NaCl

          • ethane, C2H6

          • ethene, C2H4

          • methane, CH4

          Choose your answer