O level Chemistry Practice Questions
1. What is the mass of magnesium which completely reacts with 100 cm3 of 0.25 mol/dm3 sulfuric acid?
2. What apparatus can be used to measure 21.5 cm3 of hydrochloric acid accurately?
3. Aqueous silver nitrate is added to an unknown solution P. No precipitate is observed. What ions are absent from P?
A chloride
B sulfate
C nitrate
D sodium
4. Name a compound that has both ionic and covalent bonds.
5. Carbon and chlorine can react to form a compound D. State the type of bonding in compound D and the formula of D.
6. The outer shell of an atom of element E contains 5 electrons.
(a) To which group of the Periodic Table does E belong?
(b) Draw a dot and cross diagram to show the bonding in the compound of E with hydrogen.
7. Dissolving ammonium sulfate in water is an example of
A exothermic reaction
B endothermic reaction
C precipitation reaction
D neutralization reaction
8. State the oxidation numbers of iron in FeO and Fe2O3.
9. Chlorine reacts with water to make a solution that can be used as a bleach.
Cl2 + H2O --> HCl + HOCl
Use oxidation number to show that chlorine is reduced from chlorine to hydrochloric acid in this reaction.
10. Describe in detail how you can prepare a dry sample of lead(II) chloride.
11. Write the ionic equation for the reaction of hydrochloric acid and potassium hydroxide.
12. Describe the type of oxides formed as you go across Period 3 of the Periodic Table.
13. You are provided with the following substances.
Aqueous chlorine
Aqueous iodine
Aqueous potassium chloride
Aqueous potassium iodide
Use substances from the list to show that iodine is less reactive than chlorine.
Your answer should include details of your observations and the equation for the reaction which occur. State the type of reaction that occurs.
14. A student places a rod of zinc in aqueous copper(II) sulfate.
(a) Write a balanced equation, with state symbols, for the reaction which happened.
(b) What would you expect to see after the reaction had been taking place for some time?
(c) State the type of reaction which occurs.
15. Ethanol vapour is mixed with air before being burned in a car engine in Brazil.
What are the major products of combustion of ethanol in an excess of air?
16. Aldehydes are a class of organic compounds that contain the –CHO functional group.
The table shows the name and formulae of the first few aldehydes:
Name Formula
Methanal HCHO
Ethanal CH3CHO
Propanal CH3CH2CHO
Butanal CH3CH2CH2CHO
(a) Write down the chemical name and formula of the fifth member of aldehyde.
(b) What is the molecular formula of the fifth member?
(c) Ethanal can be oxidized to ethanoic acid by an oxidizing agent. Draw the full structural formula of ethanoic acid.
17. Ethene reacts with steam to form compound F.
State the conditions for the formation of F. Identify F.
Answers:
1. Mg + H2SO4 -> MgSO4 + H2
No. Of moles of sulfuric acid = 100/1000 x 0.25 = 0.025 mol
One mole of Mg reacts with one mole of sulfuric acid.
No. Of moles of Mg = 0.025
Mass of magnesium = 0.025 x 24 = 0.600 g
2. Burette
3. A
4. Ammonium nitrate (NH4NO3)
5. D has covalent bonding in the molecule of D. Formula of D : CCl4
6(a) E belongs to Group V.
(b) EH3 [An example is NH3].
7. B
8. Fe in FeO is +2. Fe in Fe2O3 is +3.
9. Cl in Cl2 has oxidation no. 0. It is decreased to -1 in HCl. Chlorine has been reduced.
10. Brief answer: Add lead(II) nitrate solution to sodium chloride solution. Filter and dry the precipitate.
11. H+ + OH- -> H2O
12. Going from sodium to aluminium, we have metallic oxides. Silicon(IV) oxide is a giant macromolecule and an acidic oxide. Phosphorus pentaoxide, sulfur dioxide and chlorine dioxide are all acidic oxides.
13. Add chlorine to potassium iodide. Displacement occurs and a black precipitate and brown solution of iodine is obtained.
14(a) Zn (s) + CuSO4 (aq) -> ZnSO4 (aq) + Cu (s)
(b) The colour of the solution decolourises and a pink deposit of copper is observed.
(c) The reaction is displacement.
15. carbon dioxide and water. A little of carbon monoxide is obtained.
16. Fifth member : pentanal. CH3CH2CH2CH2CHO
Molecular formula : C5H10O
Draw out CH3COOH.
17. Phosphoric acid is the catalyst. 350 degree Celsius and 65 atm.
2. What apparatus can be used to measure 21.5 cm3 of hydrochloric acid accurately?
3. Aqueous silver nitrate is added to an unknown solution P. No precipitate is observed. What ions are absent from P?
A chloride
B sulfate
C nitrate
D sodium
4. Name a compound that has both ionic and covalent bonds.
5. Carbon and chlorine can react to form a compound D. State the type of bonding in compound D and the formula of D.
6. The outer shell of an atom of element E contains 5 electrons.
(a) To which group of the Periodic Table does E belong?
(b) Draw a dot and cross diagram to show the bonding in the compound of E with hydrogen.
7. Dissolving ammonium sulfate in water is an example of
A exothermic reaction
B endothermic reaction
C precipitation reaction
D neutralization reaction
8. State the oxidation numbers of iron in FeO and Fe2O3.
9. Chlorine reacts with water to make a solution that can be used as a bleach.
Cl2 + H2O --> HCl + HOCl
Use oxidation number to show that chlorine is reduced from chlorine to hydrochloric acid in this reaction.
10. Describe in detail how you can prepare a dry sample of lead(II) chloride.
11. Write the ionic equation for the reaction of hydrochloric acid and potassium hydroxide.
12. Describe the type of oxides formed as you go across Period 3 of the Periodic Table.
13. You are provided with the following substances.
Aqueous chlorine
Aqueous iodine
Aqueous potassium chloride
Aqueous potassium iodide
Use substances from the list to show that iodine is less reactive than chlorine.
Your answer should include details of your observations and the equation for the reaction which occur. State the type of reaction that occurs.
14. A student places a rod of zinc in aqueous copper(II) sulfate.
(a) Write a balanced equation, with state symbols, for the reaction which happened.
(b) What would you expect to see after the reaction had been taking place for some time?
(c) State the type of reaction which occurs.
15. Ethanol vapour is mixed with air before being burned in a car engine in Brazil.
What are the major products of combustion of ethanol in an excess of air?
16. Aldehydes are a class of organic compounds that contain the –CHO functional group.
The table shows the name and formulae of the first few aldehydes:
Name Formula
Methanal HCHO
Ethanal CH3CHO
Propanal CH3CH2CHO
Butanal CH3CH2CH2CHO
(a) Write down the chemical name and formula of the fifth member of aldehyde.
(b) What is the molecular formula of the fifth member?
(c) Ethanal can be oxidized to ethanoic acid by an oxidizing agent. Draw the full structural formula of ethanoic acid.
17. Ethene reacts with steam to form compound F.
State the conditions for the formation of F. Identify F.
Answers:
1. Mg + H2SO4 -> MgSO4 + H2
No. Of moles of sulfuric acid = 100/1000 x 0.25 = 0.025 mol
One mole of Mg reacts with one mole of sulfuric acid.
No. Of moles of Mg = 0.025
Mass of magnesium = 0.025 x 24 = 0.600 g
2. Burette
3. A
4. Ammonium nitrate (NH4NO3)
5. D has covalent bonding in the molecule of D. Formula of D : CCl4
6(a) E belongs to Group V.
(b) EH3 [An example is NH3].
7. B
8. Fe in FeO is +2. Fe in Fe2O3 is +3.
9. Cl in Cl2 has oxidation no. 0. It is decreased to -1 in HCl. Chlorine has been reduced.
10. Brief answer: Add lead(II) nitrate solution to sodium chloride solution. Filter and dry the precipitate.
11. H+ + OH- -> H2O
12. Going from sodium to aluminium, we have metallic oxides. Silicon(IV) oxide is a giant macromolecule and an acidic oxide. Phosphorus pentaoxide, sulfur dioxide and chlorine dioxide are all acidic oxides.
13. Add chlorine to potassium iodide. Displacement occurs and a black precipitate and brown solution of iodine is obtained.
14(a) Zn (s) + CuSO4 (aq) -> ZnSO4 (aq) + Cu (s)
(b) The colour of the solution decolourises and a pink deposit of copper is observed.
(c) The reaction is displacement.
15. carbon dioxide and water. A little of carbon monoxide is obtained.
16. Fifth member : pentanal. CH3CH2CH2CH2CHO
Molecular formula : C5H10O
Draw out CH3COOH.
17. Phosphoric acid is the catalyst. 350 degree Celsius and 65 atm.
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