Chemistry JAMB, WAEC, NECO AND NABTEB Official Past Questions

 (a)(1) Define each of the following terms: I. deliquescence; II. efflorescence.

(ii) Give one example I substance that undergoes each of the processes in (a)(i).

(b) Outline how three colourless gases suspected to be ethane, ethene and ethyne could be distinguished in the laboratory.

(c)(i) What is water crystallization?

(ii) Hydrated calcium chloride (CaCl\(_2\) = 111, xH\(_2\)O) contains 49.32% water of cystallization. Calm the value of x. [ (CaCl\(_2\) = 111, H\(_2\)O = 18 ]

(d) Name one calcium compound used (i) in the manufactur cement; (ii) as a dessicant; (iii) in the production of plaster of Paris (POP);

(iv) to neutralise acidic soils

(e) A concentrated solution of sodium chloride was electrolysed using graphite electrodes.

(i) State the ions present in the solution

(ii) Name the products at the I. anode, II. cathode.

(iii) Give the by-product of the electrolysis.

(a) Atoms of four non-metallic elements in the same group of the periodic table are arranged in order of increasing atomic radius as R < T < W < X. Which of the elements

(i) would readily lose electron(s) from the outermost shell;

(ii) is most electronegative;

(iii) would T displace from aqueous solution;

(iv) is at the top of the group?

(b) The following table shows the electronic configuration of two elements Y and Z.

(i) Name the I. group to which Y belongs II. period to which Z belongs.

(ii) What is the number of protons present in an atom of Z?

(iii) How many unpaired electrons are in an atom of Y?

(iv) Write the formula of the compound formed between Y and Z

(c) Name the type of bond(s) that exist(s) in each of the following compounds.

(i) CaCl\(_2\); (ii) NH\(_4\)Cl; CCl\(_4\)

(d) Describe how the conductance of a molar solution of ammonia compares to that of sodium hydroxide solution.

(e) State the type of reaction illustrated by each of the following equations:

(i) CH\(_3\)CH\(_2\)OH\(_{(/)}\) + CH\(_3\)COOH\(_{(aq)}\) \(\rightleftharpoons\) CH\(_3\)COOC\(_2\)H\(_5\)\(_{(/)}\) + H\(_2\)O\(_{(/)}\)

(ii) H+\(_{Y^+_{(aq)}\) + OH\(^+_{(aq)}\) \(\to\) H\(_2\)O

(f) Determine the volume of the residual gas when 20.0cm\(^3\) of hydrogen was sparked with 15.0cm\(^3\) of oxygen and the resulting mixture cooled to room temperature.

(a)(i) Define polymerization.

(ii) Mention two types of polymerization.

(iii) Give one example of I. naturally occurring polymer, II. synthetic polymer.

(b)(i) Describe how ethyne could be prepared in the laboratory.

(ii) Write an equation for the I. polymerization of ethyne II. complete reaction of ethyne with hydrogen bromide.

(iii) Name each of the products formed in (b)(ii) II.

(c)(i) Define each of the following terms: I. pollution; Il. pollutant.

(ii) Mention three types of pollution.

(iii) Give two ways by which pollution can be prevented.

(a) (i) State Boyle’s law.

(ii) Give the mathematical expression of Boyle’s law.

(iii) Sketch the graphical representation of Boyle’s law.

(b) A given mass of gas occupied 500 cm3 at 30°C and 6.5 x 104 Nm\(^{-2}\). Calculate the volume of the gas at s.t.p. [ Standard pressure = 1.01 x 105 Nm\(^{-2}\)]

(c) Explain why an inflated balloon expands in warm water.

(d)(i) What is meant by the term vapour density? (ii) Determine the vapour density of SO\(_{2}\). [ S = 32, O = 16 ]

(e)(i) Which of the following gases, SO\(_{2}\) and NH\(_{3}\) can be collected by I. upward delivery; II. downward delivery?

(ii) What would be the nature of the solution formed by dissolving each of the following substances in water separately. I. SO\(_{2}\) II. NH\(_{3}\)

(iii) State the property exhibited by SO\(_{2}\) and NH\(_{3}\) in the following equations:

I. 2H\(_{2}\)S\(_{(aq)}\) + SO\(_{2(g)}\) \(\to\)  3S\(_{(s)}\) + 2H\(_{2}\)O\(_{(/)}\)

II. 3CuO\(_{(s)}\) + 2NH\(_{3(g)}\)  \(\to\) 3Cu\(_{(s)}\) + 3H\(_{2}\)O\(_{(/)}\) + N\(_{2(s)}\).

(f) State two alloys of tin.

(ii) Give one use of each of the alloys in (f)(i).

(a)(i) Outline a suitable procedure for the preparation of ZnCl\(_2\) crystals stating from zinc granules.

(ii) Write a balanced equation for the reaction in (a)(i).

(b) Considei’ the following solutions: Na\(_2\)SO\(_{4(aq)}\), CH3COOK\(_{(aq)}\), Pb(NO\(_3\))\(_{2(aq)}\) and MgCl\(_2\). Which of them has/have a pH

(i) greater than 7;

(ii) equal to 7;

(iii) less than 7?

(c)(i) Determine the oxidation number of Mn in I. MnO\(_2\); II. KMnO\(_4\).

(ii) State one laboratory use of each of the .compounds in (c)(i).

(d) Explain why oxidation and reduction processes are complementary.

(e) Consider the reaction represented by the equation: Fe\(_{(s)}\) + 2Ag\(^+_{(aq)}\) \(\to\) Fe\(^{2+}_{(aq)}\) + 2Ag\(_{(s)}\)

(i) Write a balanced ionic half equations for the reaction.

(ii) Which of the species is I. oxidized; II. reduced?

(iii) State the change in the oxidation number of silver during the reaction.

(a) Name one product of destructive distillation of coal that is (i) solid (ii) liquid; (iii) gas.

(b) (i) What is the major component of synthetic gas? (ii) Give one reason why synthetic gas is not a major source of air pollution.

(c) (i) Write a balanced chemical equation for the complete combustion of carbon. (ii) State two: I. physical; II. chemical properties of the product in (c)(i).

(d) (i) Name two allotropes of carbon that are I. crystalline, II. amorphous. (ii) State one use of each of the allotropes named in (d)(i).

(e) (i) By means of balanced chemical equations only, outline the process of manufacture of H\(_2\)SO\(_4\), by contact process.

(ii) State the function of H\(_2\)SO\(_4\) in each of the following reaction equations:

I.  C\(_2\)H\(_5\)OH\(_{2(l)}\)  \(\to\) C\(_2\)H\(_{4(g)}\);

II. Pb(NO\(_{3(g)}\) + H\(_2\)SO\(_{4(g)}\) —> PbSO\(_{4(s)}\) + 2HNO\(_{3(aq)}\)

(a (i) Explain why water is referred to as a universal solvent.

(ii) Give one chemical test for water. H\(_2\)SO\(_4\)

(b) A current of 1.25A was passed through an electrolytic cell containing dil.  for 40 minutes.

(i) Write (ii) Calculate the volume of gas produced at the anode at s.t.p. (1F = 96,500 C, Molar Volume of gas at s.t.p. = 22.4 dm\(^3\) mol\(^{-3}\) ]

(C) Consider the reaction represented by the following equation: Au\(_{(s)}\) + Cl\(_{2(g)}\) \(\to\)  AuCl\(_{3(s)}\)

(I) Balance the equation

(ii) If 1.2509 of Au and 1.744g of Cl\(_2\) were mixed

I. determine which of the reactants is in excess II. calculate the excess amount [Au = 197.0, CI = 35.5]

(a)(i) Give the two reasons why soda lime is used instead of caustic soda in the preparation of methane.

(ii) List two physical properties of methane.

(iii) A hydrocarbon with a vapour density of 29 contains 82.76% carbon and 17.24% hydrogen. Determine the: I. empirical formula; II. molecular formula of the hydrocarbon. [ H = 1.00 C = 12.00 ]

(b)(i) What is meant by the term isomerism?

(ii) Draw the structures of the two isomers of the compound with the molecular formula C\(_2\)H\(_6\)O.

(iii) Give the name of each of the isomers in (b)(ii).

(iv) State the major difference between the isomers.

(c) Give three deductions that could be made from the qualitative and quantitative analysis of a given organic compound.

(d) Give one chemical test to distinguish between propene and propane.

(a) (i) Define a base according to Arrhenius concept.

(ii) Give one example of an Arrhenius base.

(iii) Identify each of the following substances in aqueous solutions as strong electrolyte, non-electrolyte or weak electrolyte.

I. C\(_{12}\)H\(_{22}\)O\(_{11}\)  II. NH\(_3\) Ill. NaOH

(iv) Write a balanced equation to represent the reaction between CH\(_3\)COOH and KOH.

(b) Calculate the volume of 0.500 mol dm\(^{-3}\) HCI required to neutralize 20.00 cm\(^3\) of 0.300 mol dm\(^{-3}\) NaOH.

(c) Give the IUPAC name of each of the following salts: (ii) NaOCI; (iii) Mg(HCO\(_3\))\(_2\).

(d)(i) Define the term standard solution.

(ii) Consider the following compounds: NaOH and Na\(_2\)CO\(_3\). Which of the compounds is suitable for the preparation of a standard alkaline solution? Give reason for your answer

(iii) Fe completely reacted with dilute HCI.

I. Write an equation for the reaction

II. If 3.08g of Fe completely reacted with 50.0 cm\(^3\) of 2.20 mol dm\(^{-3}\) HCI, calculate the relative atomic mass of the metal.

(a) (i) Define saturated solution.

(ii) Tha solubility of KNO\(_3\) at 20°C was 3.00 mol dm\(^{-3}\) If 67.0g of KNO\(_3\) was added to 250 cm\(^{-3}\) of water and stirred at 20°C, determine whether the solution formed was saturated or not at that temperature. [ KNO\(_3\) = 101.0 ]

(b) (i) Distinguish between dative bond and covalent bond.

(ii) Explain why sugar and common salt do not conduct electricity in the solid state.

(iii) State the type of intermolecular forces present in: I. hydrogen fluoride; II argon.

(iv) Consider the compounds with the following structures. S – H —- N and O – H —- N In which of the compounds is the hydrogen bend stronger? Give reason for your answer.

(c) (i) State Dalton’s Law of Partial Pressure.

(ii) If 200cm of carbon (IV) oxide were collected over water at 18°C and 700 mmHg, determine the volume of the dry gas at s.t.p. [ standard vapour pressure of water at 18°C = 15 mmHg]

 (a) i) Give the name and nature of the radiations that are emitted during radioactivity.

ii) State two differences between chemical reaction and nuclear reaction.

iii) Balance the following nuclear reactions and identify X and Y.

I. \(^{212}_{84} PO\) \(\to\) \(^{208}_{82} Pb\) + X 

II \(^{137}_{55}Cs\) \(\to\) \(^{137}_{55}Ba\) + Y 

(b) The electron configuration of an element X is: 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^5\)

(i) Deduce the atomic number of X.

(ii) To what group does X belong?

(iii) Give two properties of the group to which the element X belong.

(iv) Identify element X by name.

(v) Write a balanced equation to represent the reaction between the element X and hot concentrated NaOH.

(c)(i) Explain why: I. graphite is used as a lubricant;  II. diamond is used as an industrial cutting tool.

(ii) Write an equation to represent the reaction between aqueous HCI and NH\(_3\) solution.

(iii) Name the type of reaction represented by the equation.

(a)(i) Draw the energy profile diagram for the reaction; H\(_{2(g)}\) + I\(_{2(g)}\) \(\to\) 2Hl\(_{(g)}\); \(\Delta\)H = –13 KJ mol\(^{-1}\)

(ii) If the concentration of HI\(_{(g)}\) increases from 0.000 to 0.002 mol dm\(^{-3}\) in 80 seconds, what is the rate of t reaction?

(b)(i)Give one use of each of the following compounds: I. NaHCO\(_{3}\); II. CaSO\(_{4}\); III. CaCO\(_{3}\).

(ii) State a drying agent that can be used for each of the following gases: I. SO\(_{2}\); II. HCI; Ill. NH\(_{3}\)

(c)(i) Write an equation for the complete combustion of carbon in oxygen.

(ii) Calculate the number moles of carbon (IV) oxide produced from the complete combustion of 2.5 g of carbon. [ C = 12.0, O = 16]

(iii) Mention one use of I. carbon (II) oxide; II. carbon (IV) oxide.

(d) An industrial raw material has the following composition by mass:

Iron = 28.1%; Chlorine = 35.7%; Water cf crystallization = 36.2%.

Calculate the formula for the material. [H = 1.00, O = 16.0, CI = 35.5, Fe = 56.0]

(e) Give one example of a (i) metal that is liquid at room temperature,

(ii) non-metal that is liquid room temperature.
 

(a) A compound X reacts with excess HNO\(_{3(aq)}\) to give carbon (IV) oxide and another compound Y. A solution of Y reacts with NaOH\(_{(aq)}\) to form a white precipitate which is insoluble in excess NaOH\(_{(aq)}\). Identify X and Y.

(b) (i) Write a balanced equation to illustrate the reducing property of ammonia in its reaction with CuO.

(ii) Explain why it is not advisable to heat ammonium dioxonitrate (III) directly.

(iii) Give two uses nitrogen.

(c) Give the reason why (i) dilute H\(_{2}\)SO\(_{4}\) is not suitable for the preparation of CO\(_{2(g)}\) from CaCO\(_{3(s)}\) (ii) concentrated H\(_{2}\)SO\(_{4}\) cannot be used to dry ammonia gas.

(d) State two: (i) physical properties; (ii) chemical properties of metals.

(e) What is the oxidation number of: (i) chlorine in I. Cl\(_{2}\). II. ClO\(_{-(3)}\)

(ii) vanadium in V\(_{2}\)O\(_{5}\)

(f)(i) Explain the term half-life. (ii) Two radioactive elements, P and Q have half-life of 1200 seconds and 3600 seconds respectively.

I. Which of the elements is more stable? II. Give a reason for your answer.

(a)(i) What is a functional group?

(ii) State the functional group in each of the following compounds: I. CH\(_3\)CH\(_2\)CH(CH\(_3\))OH; II. CH\(_3\)CH\(_2\)CH\(_2\)COOH.

(b)(i) Complete the following equations:

(ii) Draw the structure(s) of the product(s) formed in (b)(i) above.

(c)(i).Write an equation for the prepzration of butan-2-ol from butene.

(d) (i) Give the reagents required for the following conversions to take place: I. CH\(_2\) = CH\(_2\) to CH\(_3\)CH\(_2\)OH; II. CH\(_3\)CH\(_2\)OH to CH\(_3\)COOH; Ill. CH\(_3\)COOH to CH\(_3\)COOCH\(_2\)CH\(_3\).

(e) Consider the following organic structure; CH\(_3\)OHCHCH = CHCOOH

(i) State what would be observed when the organic compound is treated with each of the following reagents: I. cold NaHCO\(_{3(aq)}\); II. hot solution of I\(_2\) in NaOH\(_{(aq)}\); Ill. bromine water.

(a)Define the term solubility.

(b) The table below gives the solubility of salt Z at various mperatures

(i) Plot a graph of solubility against temperature.

(ii) From the graph determine the solubility of salt Z at 35°C.

(iii) If 100cm\(^{-3}\) of the saturated solution is cooled from 55°C to 35°C, calculate the mass of salt Z that would crystallize out. [Molar mass of salt Z = 100 g]

(c)(i) Write a balanced equation to illustrate the reaction of AI\(_2\)O\(_3\) with dilute I. HCI; II. NaOH.

(ii) What is the name given to an oxide that exhibits both acidic and basic properties?

(iii) Give one metallic oxide which exhibite these properties.

(d)(i) Determine the oxidation number of: I. Al in [Al (H\(_2\)O)\(_6\)]\(^{3+}\); II. H in NaH.

(ii) Give the IUPAC name of each of the following substances; I. CuSO\(_4\).5H\(_2\)O; II. CaCO\(_3\); Ill. KMnO\(_4\).

The following table gives the atomic numbers of elements V, W, X, Y and Z.

(a)Which of the elements: (i) belong(s) to group 1?

(ii) is/are riotle gas(es)?

(iii) form(s) coloured compound(s)?

(iv) form(s) an anion?

(v) react(s) with water to liberate hydrogen?

(vi) react(s) with water to form alkaline solution?

(b) What is the:

(i) charge on the ion formed in

(a)(iv) above?

(ii) group of the element(s) in (a)(i) above?

(c)(i) Write the formula of the compound formed between element V and element W.

(ii) Sate the type of bond formed in (c)(i) above. Explain your answer.

(d)(i) What is a covalent compound?

(ii) Give two factors that influence covalent bonding.

(iii) State the type of bond that exists in each of the following substances: MgO, NH\(_3\) and Fe.

(iv) What are intermolecular forces?

(a)The table below gives the volume/pressure data for a particular sample of a gas-at a given temperature.

(i) Deduce a mathematical relationship between volume (V) and pressure (P).

(ii) Name law that can be deduced from the data.

(iii) Calculate the pressure of the gas when the volume is 3.20 dm\(^3\)

(b)(i) What is the role of a salt bridge in an electrochemical cell?

(ii) What type of ions must flow into the cathode? Give a reason for your answer.

(iii)A standard galvanic cell constructed with Ag\(^+_{(aq)}\) Ag\(_{(s)}\) and Zn\(^{2+}_{(aq)}\) couple is discharged until 3.3 g of Ag forms.

I. Write the overall cell reaction and standard cell potential?

II. How many moles of electrons flowed through the circuit during the discharge?

III. How many coulombs of charges flowed through the circuit?

Ag\(^+_{(aq)}\) + e\(^-\) \(\rightleftharpoons\) Ag\(_{(s)}\); E° = + 0.80V

Zn\(^{2+}_{(aq)}\) + 2\(^-\)  \(\rightleftharpoons\) Zn\(_{(s)}\), E° = – 0.76 V [Ag = 108]

(c)(i) Define each of the following terms: I. Activation energy; II. Exothermic reaction.

(ii) Give one example of an endothermic process.

(iii) What is the significance of activated complex in a chemical reaction?

 (a) Define each of the following terms: I. biotechnology; II. biogas.

(ii) State two applications of biotechnology

(b) (i) Describe briefly the production of ethanol from sugar cane juice.

(ii) State the by-product of the process in (b)(i)

(iii) Mention two uses of the by-product.

(iv) Ethanol can be produced from both cane sugar and petroleum. Explain briefly why the ethanol from cane sugar is renewable but that from petroleum is non-renewable.

(c) Distinguish between heavy chemicals and fine chemicals. Give one example of each chemical.

(d) Arrange the following gases in increasing order of deviation from ideal gas behaviour: HCl; O\(_2\); Cl\(_2\). Give reason(s) for your answer.

 (a) (i) Define standard electrode potential.

(ii) State two factors that affect the value of standard electrode potential.

(iii) Give two uses of the values of standard electrode potential.

(iv) Draw and label a diagram for an electrochemic cell made up of Cu\(^{2+}\)/Cu; E° = +0.34 V  Zn\(^{2+}\)/Zn; E° = -0.76 V

(v) Calculate the e.m.f. of the cell in (a)(iv) above.

(b) (i) In terms of electron transfer, define: I. oxidation; II. oxidizing agent.

(ii) Balance the following redox reaction: MnO\(^{-4}\) + l\(^{-}\) \(\to\) l\(_{2}\) + Mn\(^{2+}\)

(c) Classiify each of the following oxides as basic, amphoteric, acidic or neutral: (i) Carbon (II) oxide; (ii) Sulphu (IV) oxide; (iii) Aluminium oxide; (iv) Lithium oxide.

(d) What is hydrogen bonding?

(a) (i) What is a structural isomer?

(ii) Write all the structural isomeric alkanols with the molecular formula C\(_4\)H\(_{10}\)O.

(iii) Which of the isomers from (a)(ii) above does not react easily on heating with acidified K\(_2\)Cr\(_2\)O\(_7\)?

(b) Chlorine reacted with excessentane in the presence of light. Chloropentane and a gas which fumes on cont with air were produced.

(i) Write an equation for the reaction.

(ii) Draw the structure of the major product.

(iii) What is the role of light in the reaction?

(iv) If a mixture of pentane and the major product is heated, which compounc would distil off first? Give a reason for your answer.

(v) Write the formula of the main product that would have be formed if but -1-ene has been used instead of pentane.

(c) Give the name and structural formula of the product which would be formed by hydration of each of the followinc compounds:

(i) CH\(_3\)CH(CH\(_3\))CH=CH\(_2\); (ii) CH\(_2\)=CHCOOH.

(d) (i) Write the structure of the amino acid, CH\(_3\)CH(NH\(_2\))COOH in: I. acidic medium; II. alkaline medium.

(ii) On analysis, an ammonium salt cf an alkanoic acid gave 60.5% carbon and 6.5% hydrogen. If 0.309 g of the salt yielded 0.0313 g of nitrogen, determine the empirical formula cf the salt. [H = 1.00; C =12.0; N =14.0; O = 16.0]

(a) (i) Define nuclear fission.

(ii) A certain natural decay series starts with \(^{238}_{92}U\) and ends with\(^{230}_{90}Th\). Each step involves the loss of an alpha or a beta particle. Using the given information, deduce how many alpha beta particpes were emitted.

(b) Consider the equilibrium reaction represented by the following equation:

A\(_{2(9)}\) + 3B\(_{2(9)}\) \(\rightleftharpoons\) 2AB\(_{3(g)}\); \(\Delta\)H = + xkJmol\(^{-1}\)

Explain briefly the effect of each of the following changes on the equilibrium composition: (i) increase in concentrat of B; (ii) decrease in pressure of the system; (iii) addition of catalyst.

(c) The lattice energies of three sodium halides are as follows:

Explain briefly the trend.

(d) State the property exhibited by nitrogen (IV) oxide in each of the following reactions:

(i) 4Cu + 2NO\(_2\) \(\to\)  4CuO + N\(_2\);

(ii) H\(_2\)O +  2NO\(_2\) \(\to\) HNO\(_3\) + HNO\(_2\).

(e) Iron is manufacturcd in a blast furnace using iron ore (Fe\(_2\)O\(_3\)), coke and limestone. Write the equation for the reaction(s) at the: (i) top of the furnace; (ii) middle of the furnace; (iii) bottom of the furnace.

(f) (i) Name two products of destructive distillation of coal. (ii) Give one use of each product in (f)(i).