The 2023 Chemistry Essay answer paper will start at 9:30 am and will last for 2hrs while the Objective exam will commence at 11:30 pm and will last for 1hr.<\/p>\r\n
In this post, we will be posting the West African Senior School Certificate Examinations (WASSCE) Chemistry questions for candidates who will participate in the examination from past questions.<\/p>\r\n
![\"waec](\"https:\/\/unn-edu.info\/wp-content\/uploads\/2017\/09\/waec-chemistry-questions.jpg\")
<\/p>\r\n
Continue reading below.<\/p>\r\n
WAEC Chemistry Answers 2024.<\/strong><\/h3>\r\nPAPER 2 [Essay]<\/strong>
Answer any <\/em>FOUR<\/strong> questions.<\/em>
Write your answers on the answer booklet provided.<\/em><\/p>\r\n1. (a) (i) What is the common name given to the group VII elements?
(ii) Name the hydrides of the first two elements in group VII.
(iii) State three chemical properties of group VII elements.<\/p>\r\n
(b) Copy and complete the following table<\/p>\r\n
\r\n\r\n\r\n\r\nParticles<\/p>\r\n<\/td>\r\n
\r\nNumber of neutrons<\/p>\r\n<\/td>\r\n
\r\nNumber of electrons<\/p>\r\n<\/td>\r\n
\r\nNumber of Protons<\/p>\r\n<\/td>\r\n
\r\nMass Number<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nW2+<\/p>\r\n<\/td>\r\n
\r\n12<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n24<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nX2-<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n8<\/p>\r\n<\/td>\r\n
\r\n16<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nY<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n13<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n27<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nZ<\/p>\r\n<\/td>\r\n
\r\n12<\/p>\r\n<\/td>\r\n
\r\n11<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n
\r\n\u00a0<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n
(c) (i) Define each of the following processes: nuclear fission; nuclear fusion.
\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0
(ii) Give one use of each process in 1(c)(i)<\/p>\r\n
(d) (i) List three types of radiation that are produced during radioactivity.
(ii) Arrange the radiations listed in 1(d)(i) in order of increasing: penetrating power; ionizing power.<\/p>\r\n
ANS: <\/strong>(a) (i) Halogens\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0
(ii)\u00a0 Hydrogen fluoride; Hydrogen chloride\u00a0\u00a0\u00a0\u00a0\u00a0
(iii) high electron affinity\/strong oxidizing agents\/electron acceptor
– highly electronegative;
– react with hydrogen to form acid;
– form salts with metals;
– react with alkalis to form salts;
– react with water to form acids;
\u00a0– displacement of lower halogens from their acids\/salts;
– react with hydrocarbon to form alkyl halides.
(b)<\/p>\r\n\r\n\r\n\r\nParticles<\/td>\r\n \r\nNumber of neutrons<\/p>\r\n<\/td>\r\n
\r\nNumber of electrons<\/p>\r\n<\/td>\r\n
\r\nNumber of Protons<\/p>\r\n<\/td>\r\n
\r\nMass Number<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nW2+<\/p>\r\n<\/td>\r\n
\r\n12<\/p>\r\n<\/td>\r\n
\r\n10<\/p>\r\n<\/td>\r\n
\r\n12<\/p>\r\n<\/td>\r\n
\r\n24<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nX2-<\/p>\r\n<\/td>\r\n
\r\n8<\/p>\r\n<\/td>\r\n
\r\n10<\/p>\r\n<\/td>\r\n
\r\n8<\/p>\r\n<\/td>\r\n
\r\n16<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nY<\/p>\r\n<\/td>\r\n
\r\n14<\/p>\r\n<\/td>\r\n
\r\n13<\/p>\r\n<\/td>\r\n
\r\n13<\/p>\r\n<\/td>\r\n
\r\n27<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\nZ<\/p>\r\n<\/td>\r\n
\r\n12<\/p>\r\n<\/td>\r\n
\r\n11<\/p>\r\n<\/td>\r\n
\r\n11<\/p>\r\n<\/td>\r\n
\r\n23<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n
(c)(i) I. Nuclear fission \u2013 splitting of a heavy nucleus into two smaller nuclei of similar mass with the release of a large amount of energy and radiation.
II. Nuclear fusion \u2013 a combination of smaller nuclei to form a large nucleus with the release of large amounts of energy and radiation.
(ii) I. Used to generate electricity\/nuclear bomb\/production of new elements\/production of\u00a0radioisotopes.
II. Used to produce nuclear weapons\/atomic bombs\/production of new elements\/production radioisotopes.
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0
(d) (i)\u00a0 alpha, beta, gamma OR \u03b1 ,\u00a0\u00a0\u00a0 \u03b2,
(ii)\u00a0 I.\u00a0\u00a0\u00a0 \u03b1\u00a0\u00a0 <\u00a0\u00a0\u00a0 \u03b2 \u00a0\u00a0\u00a0<\u00a0 increasing penetrating power
II.\u00a0\u00a0 <\u03b2\u00a0\u00a0\u00a0\u00a0 <\u00a0\u00a0 \u03b1 increasing ionizing power.<\/p>\r\n
2. (a) (i) What is the structure of the atom as proposed by Rutherford?
(ii) Distinguish between the atomic number and the mass number of an element.
(iii) Explain briefly why the relative atomic mass of chlorine is not a whole number.<\/p>\r\n
(b)\u00a0(i) What is meant by first ionization energy?
(ii) List\u00a0three\u00a0properties of electrovalent compounds
(iii) Consider the following pairs of elements:
9F and 17CL;
12Mg and 20Ca.
Explain briefly why the elements in each pair have similar chemical properties.<\/p>\r\n
(c)\u00a0Explain\u00a0briefly\u00a0the following terms using an appropriate example in each case
(i) homologous series;
(ii) heterolytic fission.<\/p>\r\n
(d)\u00a0State the indicator(s) which could be used to determine the end-point of the following titrations:
(i) dilute hydrochloric acid against sodium hydroxide solution;
(ii) dilute hydrochloric acid against ammonium hydroxide solution;
(iii) ethanoic acid against sodium hydroxide solution.<\/p>\r\n
(e) A solid chloride E which sublimed on heating reacted with an alkali F to give a choking gas G. G turned moist red litmus paper blue.\u00a0 Identify E, F and G.<\/p>\r\n
ANS:\u00a0<\/strong>(a) (i) The atom has a small\/ tiny positively charged centre \/nucleus with electrons surrounding the space around the centre. \u00a0
(ii) Atomic number of an element is the number of protons\/electrons in an atom of the element while the mass number is the sum of the protons and neutrons in the atom of the element.
(iii) Chlorine atom is made up of a mixture of isotopes and the relative atomic mass of chlorine is the average of its isotopic masses.<\/p>\r\n(b) (i) Is the (minimum) energy required to remove\u00a0one mole\u00a0of an electron from\u00a0one mole\u00a0of gaseous atom (to form one mole gaseous charged ion
(ii) High melting \/boiling point;
Ability to conduct electricity in the molten state or in solution;
Solid at room temperature;
Soluble in water or polar solvents \/insoluble in non-polar solvents.
(iii) Atoms of the elements in each pair have the same number of electrons in their outer-most shell therefore similar chemical properties.<\/p>\r\n
(c) (i) Is a family of organic compounds:
– where successive members differ by \u2013CH2 of the molar mass of 14;
– with similar chemical properties;
– which conform to the same general formula;
– which show a gradation of physical properties;
– which have the same general method of preparation. e.g \u00a0alkanes, alkenes , alkanols.
(ii) Is a process in which a (covalent) bond is broken in such a way that the electron pair is completely transferred to one of the atoms (resulting in the formation of ions)
H \u00f7 CI\u00a0\u00a0\u00a0\u00a0 \u2192\u00a0\u00a0\u00a0\u00a0\u00a0 H+ + Cl-\/ HCl \u00ae H+ + Cl-
(d)(i) Methyl orange\/ methyl red\/ phenolphthalein;
(ii) Methyl orange\/ methyl red;
(iii) Phenolphthalein.
(e) E\u00a0 \u00a0–\u00a0 \u00a0NH4Cl
F\u00a0 –\u00a0 NaOH, KOH, or Ca (OH)2, \u00a0Li OH, CsOH, Ba(oH)2, Mg(OH)2
G\u00a0 –\u00a0 \u00a0NH3.<\/p>\r\n
3. (a) (i) Define saturated solution.\u00a0
(ii) The solubility of KN03\u00a0at 20\u00b0C was 3.00 mol dm-3\u00a0If 67.0g of KN03\u00a0was added to 250cm3\u00a0of water and stirred at 20\u00b0C, determine whether the solution formed was saturated or not at that temperature.<\/p>\r\n
(b) (i) Distinguish between the dative bond and covalent bond.\u00a0
(ii) Explain why sugar and common salt do not conduct electricity in the solid state.\u00a0
(iii) State the type of intermolecular forces present in
I. hydrogen fluoride;
II. argon.\u00a0
(iv) Consider the compounds with the following structures:\u00a0
S – H —-N and 0 – H —–N\u00a0
In which of the compounds is the hydrogen bond stronger? Give a reason for your answer.<\/p>\r\n
(c) (i) State\u00a0Dalton’s\u00a0Law of Partial Pressure.
(ii) If 200cm3\u00a0of carbon(IV) oxide were collected over water at 18\u00b0C and 700 mmHg, determine the volume of the dry gas at s.t.p.[ standard vapour pressure of water at 18\u00b0C\u00a0= 15\u00a0mmHg]\u00a0<\/p>\r\n
ANS: <\/strong>(a) (i) Is a solution that contains the maximum amount of solute it can dissolve at a given temperature (in the presence of undissolved solute).
(ii)\u00a0Solubility of KN03 in in g dm-3\u00a0= 3.00 x 101 = 303\u00a0
.. 1000cm3\u00a0of saturated solution = 303g\u00a0
250cm3\u00a0of the solution = 303 x 250\u00a0<\/u>
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01000\u00a0\u00a0
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0= 75.8 g
Since the quantity of KN03 added (67.0) to 250 cnr’ of water is less than the maximum amount required to form a saturated solution, then the solution is unsaturated.<\/p>\r\n(b)(i) In a dative bond, only one of the participating atoms\/ species donated electrons to be shared by both atoms while in a covalent bond both participating atoms\/ species contribute equally to the electrons being shared.\u00a0
(ii) Sugar is covalent while common salt (NaCl) is electrovalent\/ ionic. Electrical conductivity (in compounds) depends on the presence of mobile ions.
(iii) The intermolecular forces present in hydrogen fluoride and argon were hydrogen bond and van der Waal’s forces respectively.\u00a0
(iv) 0 – H —- N has a stronger hydrogen bond because oxygen is more electronegative and smaller in size than sulphur.\u00a0<\/p>\r\n
(c)(i) the total pressure exerted by a mixture of gases that do not react chemically is equal to the sum of the individual partial pressures of the gases in the mixture.
(ii)\u00a0pressure of the dry gas (P 1) = 700 – 15 = 685 mmHg\u00a0
VI = 200cm3<\/sup>, TI = 18\u00b0C = 273 + 18 = 291K, P2 = 760 mmHg,\u00a0
T2 = 273\u00a0
P1V1<\/u>\u00a0=\u00a0P2V2<\/u>\u00a0
\u00a0 T1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 T2
V2 =\u00a0P1V1T<\/u>2\u00a0\u00a0 =\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 P2T1<\/p>\r\n= 685 x 200 x 273\u00a0
<\/u>\u00a0\u00a0\u00a0760 x 291<\/p>\r\n
= 169.1cm3<\/sup><\/span><\/p>\r\n4. (a) (i) Define nuclear fission
(ii) A certain natural decay series starts with and ends with. Each step involves the loss of an alpha or a beta particle. Using the given information,\u00a0 deduce how many alpha and beta particles were emitted.
(b) Consider the equilibrium reaction represented by the following equation: A2(g)\u00a0 +\u00a0 3B2(g)\u00a0 \u00a0 2AB3(g);\u00a0\u00a0\u00a0 H\u00a0\u00a0 =\u00a0 +\u00a0 kJmol-1
Explain briefly the effect of each of the following changes on the equilibrium composition;
(i)\u00a0 increase in the concentration of B;
(ii) decrease in pressure of the system;
(iii) addition of catalyst.
(c) The lattice energies of three sodium halides are as follows:<\/p>\r\n
\r\n\r\n\r\n\r\nCompound<\/p>\r\n<\/td>\r\n
\r\nNaF<\/p>\r\n<\/td>\r\n
\r\nNaBr<\/p>\r\n<\/td>\r\n
\r\nNaI<\/p>\r\n<\/td>\r\n<\/tr>\r\n
\r\n\r\n\u00a0Lattice energy\/kJmol-1<\/p>\r\n<\/td>\r\n
\r\n890<\/p>\r\n<\/td>\r\n
\r\n719<\/p>\r\n<\/td>\r\n
\r\n670<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n
Explain briefly the trend.<\/p>\r\n
(d) State the property exhibited by nitrogen (IV) oxide in each of the following reactions:
(i) 4Cu\u00a0 +\u00a0 2NO2\u00a0 \u00a0 \u00a0 \u00a0 4CuO + N2;
(ii) H2O+ 2NO2\u00a0 \u00a0 \u00a0 \u00a0 HNO3\u00a0\u00a0 + HNO2<\/p>\r\n
(e) Iron is manufactured in a blast furnace using iron ore (Fe2O3), 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\u00a0products of destructive distillation of coal.
(ii) Give\u00a0one\u00a0use of each product in\u00a03(f)(i).<\/p>\r\n
5. Copy and complete the following table:<\/p>\r\n
\r\n\r\n\r\nOxide of nitrogen<\/td>\r\n Oxidation state of nitrogen<\/td>\r\n Colour of gas<\/td>\r\n Solubility in water<\/td>\r\n Action on damp blue litmus paper<\/td>\r\n<\/tr>\r\n \r\nN2O<\/td>\r\n + 1<\/td>\r\n \u00a0<\/td>\r\n Insoluble<\/td>\r\n \u00a0<\/td>\r\n<\/tr>\r\n \r\nNO<\/td>\r\n \u00a0<\/td>\r\n Colourless<\/td>\r\n \u00a0<\/td>\r\n \u00a0<\/td>\r\n<\/tr>\r\n \r\nNO2<\/td>\r\n \u00a0<\/td>\r\n \u00a0<\/td>\r\n \u00a0<\/td>\r\n \u00a0<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n(i) Mention\u00a0one<\/strong>\u00a0compound that makes water
I. temporarily hard;
II. permanently hard.
(ii) State\u00a0one\u00a0<\/strong>method that could be used to remove
I. only temporary hardness;
II. permanent hardness.
(iii) Write an equation to show the removal of:
I. temporary hardness;
II. permanent hardness.
(c) (i) List\u00a0three<\/strong>\u00a0sources of water pollution.
(ii) Mention\u00a0two<\/strong>\u00a0ways by which water pollution can be controlled.
(d) state the function of\u00a0each<\/strong>\u00a0of the following substances in the purification of water for town supply:
I. sodium aluminate (III) (NaAIO2);
II. lime (calcium hydroxide);
III. calculated mount of iodine;
IV. sand bed.<\/p>\r\n6. (a) (i) What is meant by atomicity?
(ii) Mention\u00a0one\u00a0element in\u00a0each\u00a0case which is
I. monatomic,
II. diatomic,
III. tetratomic.
(iii) Write the orbital electron configuration of
I. 20Ca,
II. 9F.
a. In which group does each of the elements belong?
b. How many unpaired electrons are present in 9F?
c. How many electrons are present in 20Ca2+?<\/p>\r\n
(b) (i) Write a balanced equation for the thermal decomposition of KC\u0196O3.
(ii) Mention the catalyst that could be used to increase the rate of reaction in 6(b)(i).
(ii) If 5.0 g of KC\u0196O3 was decomposed by heat, determine the volume of oxygen produced at s.t.p.
[Molar gas volume at s.t.p. = 22.4dm3, K = 39,\u00a0 Cl = 35.5, O = 16]<\/p>\r\n
(c) (i) Mention the products formed when\u00a0each\u00a0of the following substances is heated strongly:
I. ZnCO3;
II. CuSO4.5H2O.
(ii) State the colour change observed when\u00a0each\u00a0of the residues in 1(d)(i) above is allowed to cool.<\/p>\r\n
7.\u00a0(a) Describe\u00a0briefly\u00a0how\u00a0each\u00a0of the following aqueous solutions could be identified in the laboratory:
(i) Ammonium trioxocarbonate (IV);
(ii)Ammonium chloride.
(b) Arrange the following compounds in order of increasing boiling point and give reasons for your answer:\u00a0CS2, \u00a0NaF and CO2.
(c) List\u00a0two\u00a0gases\u00a0each\u00a0that are:
(i) acidic;
(ii) highly soluble in water;
(iii) oxidized by acidified KMnO4(aq).
(d) In a tabular form, compare the elements silicon and sulphur under the following properties:
(i) metallic character;
(ii) physical state;
(iii) conduction of electricity.
(e) A cuboid piece of sodium metal measures 3 cm x 4 cm x 10 cm. If the density of sodium is\u00a00.971 g cm-3, calculate the number of atoms in the sodium metal.
[ Na = 23; Avogadro constant = 6.02 x 1023 mol_1 ]<\/p>\r\n
![\"waec](\"https:\/\/unn-edu.info\/wp-content\/uploads\/2017\/09\/waec-gce-chemistry-answer-2017.jpg\")
<\/p>\r\n
8.\u00a0(a)\u00a0 (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 electrochemical cell made up of
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Cu2+\/Cu;\u00a0 \u00a0= + 0.34\u00a0
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Zn2+\/Zn;\u00a0 \u00a0= – 0.76
(v) Calculate the e.m.f of the cell in 8(a)(iv) above
(b) (i)\u00a0 In terms of electron transfer, define
I. oxidation;
II. oxidizing agent.
(ii) Balance the following redox reaction: MnO4-\u00a0\u00a0\u00a0 +\u00a0 I-\u00a0H+\u00a0\u00a0 I2Mn2+<\/p>\r\n
(c) Classify each of the following oxides as basic, amphoteric, acidic or neutral:
(i) Carbon (II) oxide;
(ii) Sulphur(IV) oxide;
(iii) Aluminium oxide;
(iv) Lithium oxide.<\/p>\r\n
(d) What is hydrogen bonding?<\/p>\r\n
9.\u00a0<\/p>\r\n
WAEC Chem Objective Questions 202<\/strong>4<\/strong>.<\/strong><\/h4>\r\nPAPER 1 [Essay]<\/strong>
Answer <\/em>All<\/strong> questions in this section.<\/em>
Write your answers on the answer sheet provided.<\/em><\/p>\r\n1.\u00a0Two immiscible liquids with different boiling points can be separated by\u00a0_____
A. The use of separating funnel
B. Evaporation
C. Distillation
D. Decantation.<\/p>\r\n
2. A mixture of CaCl2 and CaCO3 in water can be separated by\u00a0\u00a0______
A. Evaporation
B. Sublimation
C. Distillation
D. Decantation.<\/p>\r\n
3.\u00a0What is responsible for metallic bonding?
A. sharing of electrons between the metal atoms
B. attraction between the atomic nuclei and the cloud of electrons
C. Transfer of electrons from one atom to another
D. attraction between positive and negative ions.<\/p>\r\n
4. 25cm3 of 1.5M solution of NaCl are added to 50cm3 of 3M NaCl. The molar concentration of the resulting solution is ________
A. 2.5M\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 B. 3M\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 C. 2.25M\u00a0\u00a0\u00a0\u00a0 D. 4.5M<\/p>\r\n
5. A solution of salt formed from HCl and NH3 solutions is\u00a0_____
A. Acidic\u00a0 \u00a0 \u00a0B. Basic\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 C. complex\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 D. Neutral<\/p>\r\n
6. Which of the following elements will burn in excess oxygen to form a product that is neutral to litmus?\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A. carbon\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 B. Hydrogen\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 C. Sulphur\u00a0 \u00a0 \u00a0 \u00a0 D. Sodium<\/p>\r\n
7. A current was passed for 10 mins and 0.2mole of Cu was deposited. How many grammes of Ag will it deposit?
(Cu = 64, Ag = 108)
A. 43.2g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 B. 21.6g\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0C. 10.8g\u00a0\u00a0\u00a0 D. 5.4g<\/p>\r\n
8. Pollution of underground water by metal ions is very likely in a soil that has high\u00a0\u00a0________
A. Acidity\u00a0 \u00a0 \u00a0 \u00a0B. Alkalinity\u00a0 \u00a0 \u00a0 \u00a0 C. Chloride content\u00a0\u00a0\u00a0\u00a0 D. Nitrate content<\/p>\r\n
9. Producer gas is a gas with low caloric value because it contains more\u00a0____
A. CO2 than O2\u00a0 \u00a0 \u00a0 B. N2 than CO\u00a0 \u00a0 \u00a0C. CO2 than N2\u00a0 \u00a0 \u00a0D. N2 than CO2<\/p>\r\n
10.\u00a0Silver chloride turns grey when exposed to sunlight because _____
A. The silver ion is reduced to silver
B. The silver ion is oxidized to silver
C. Silver is a transition metal
D. The silver chloride forms complexes in the sun.<\/p>\r\n
11. Which of these compounds exhibits resonance?
A. Benzene\u00a0\u00a0 B. Ethanol\u00a0\u00a0\u00a0 C. Propene\u00a0\u00a0\u00a0 D. Butyne<\/p>\r\n
15. Hydrolysis of CH3COOCH2CH3 in dilute HCl produces ______
A. CH3COOH + CH3CH3
B. CH3CH2OH + CH3COCl
C. CH3COOH + CH3CH2OH
D. CH3COOH + CH3CH3<\/p>\r\n
16.\u00a0Calculate the volume of CO2 measured at s.t.p produced on heating 250g of potassium hydrogen trioxocarbonate (IV) strongly.
\u00a0(K = 39, H = 1, C = 12, O = 16)
\u00a0A. 28dm3 \u00a0\u00a0B. 2.8dm3\u00a0 C.5.6dm3 \u00a0D. 11.2dm3<\/p>\r\n
17. The boiling points of water, ethanol, methylbenzene and butan-2-ol are 373.0K, 351.3K, 383.6K and 372.5K respectively. Which liquid has the highest vapour pressure at 323.0K?
A. Water\u00a0 \u00a0 \u00a0 B. Methylbenzene\u00a0 \u00a0 \u00a0 \u00a0C. Ethanol\u00a0 \u00a0 \u00a0 \u00a0D. Butan-2-ol<\/p>\r\n
18. The conclusion from Rutherford\u2019s alpha scattering experiment is that\u00a0______
A. Atoms are mostly empty space with a small nucleus
B. Emissions from radioactive substances consist of three main components
C. There is a nuclear pull on orbital electrons
D. Electrons are deflected by both magnetic and electric fields.<\/p>\r\n
19. Elements P, Q and R have atomic numbers 9, 16 and 20 respectively. Which of them would gain electron(s) during ionic bonding\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A. Q and R
B. P and R
C. P and Q
D. P, Q and R.<\/p>\r\n
20. Which of the following has the lowest PH?
A. 5cm3 of M\/10 HCl
B. 10cm3 of M\/10 HCl
C. 20cm3 of M\/8 HCl
D. 15cm3 of M\/2 HCl<\/p>\r\n
21. Which of the following is an acid salt?
A. (NH4)2CO3\u00a0 \u00a0 \u00a0B. CHCOONa\u00a0\u00a0 C. KHSO4\u00a0 \u00a0\u00a0\u00a0D. MgSO4.7H2O<\/p>\r\n
22. Cr2O2-7 + 14H+\u00a0 + 6I \u2192 2Cr3+\u00a0 + 3I2\u00a0 + 7H2O. The change in the oxidation number of oxygen in the equation above is _______
A. 0\u00a0 \u00a0 \u00a0 \u00a0B. 1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 C. 2\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 D. 7<\/p>\r\n
23. During electrolysis of CuSO4 solution using platinum electrodes, which of the following occurs\u00a0______
A. Acidity increases at the cathode
B. Oxygen is liberated at the cathode
C. PH decreases at the cathode
D. PH of solution increases.<\/p>\r\n
24. Which of the following ions is a pollutant in drinking water even in trace quantities?
A. Ca2+\u00a0 \u00a0 B. Pb2+\u00a0\u00a0\u00a0 C. Mg2+\u00a0\u00a0\u00a0\u00a0 D. Fe2+<\/p>\r\n
25.\u00a0The solubility of a salt of molar mass 100g at 20oC is 0.34mol\/dm3. If 3.4g of that\u00a0salt dissolved completely 250cm3 of water at that temperature, the resulting solution is ________
A. A suspension
B. Saturated
C. Unsaturated
D. Supersaturated<\/p>\r\n
26. Catalyst is important in in chemical industry in that\u00a0______
A. it affects the purity of the products
B. it affects the quantity of the products
C. it increases the time for reaching equilibrium
D. Bond breaking is slowed down.<\/p>\r\n
27. An alkanioc acid has a molecular mass of 88. Name the acid.
(C = 12, O =16, H = 1)
A. Propanioc acid
B. Botanioc acid
C. Pentanioc acid
D. But-2-ionic acid<\/p>\r\n
28. Ethyne undergoes the following reactions EXCEPT
A. Polymerization\u00a0\u00a0 B. Addition\u00a0 C. Combustion \u00a0\u00a0\u00a0D. Etherification<\/p>\r\n
29.\u00a0<\/p>\r\n
Keep following, more questions and answers will be added soon.<\/strong><\/p>\r\nPS:<\/strong> Once again, there is nothing like waec chemistry expo. Do not fall victim to scammers online trying to obtain money from you with fake promises of having access to live question paper before the exam. What we have on this page are likely exam questions from waec past questions and answers to serve as a revision guide.<\/p>\r\n
Answer any <\/em>FOUR<\/strong> questions.<\/em>
Write your answers on the answer booklet provided.<\/em><\/p>\r\n
1. (a) (i) What is the common name given to the group VII elements?
(ii) Name the hydrides of the first two elements in group VII.
(iii) State three chemical properties of group VII elements.<\/p>\r\n
(b) Copy and complete the following table<\/p>\r\n
| \r\n Particles<\/p>\r\n<\/td>\r\n | \r\n Number of neutrons<\/p>\r\n<\/td>\r\n | \r\n Number of electrons<\/p>\r\n<\/td>\r\n | \r\n Number of Protons<\/p>\r\n<\/td>\r\n | \r\n Mass Number<\/p>\r\n<\/td>\r\n<\/tr>\r\n | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| \r\n W2+<\/p>\r\n<\/td>\r\n | \r\n 12<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n 24<\/p>\r\n<\/td>\r\n<\/tr>\r\n | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| \r\n X2-<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n 8<\/p>\r\n<\/td>\r\n | \r\n 16<\/p>\r\n<\/td>\r\n<\/tr>\r\n | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| \r\n Y<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n 13<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n 27<\/p>\r\n<\/td>\r\n<\/tr>\r\n | |||||||||||||||||||||||||||||||||||||||||||||||||||||
| \r\n Z<\/p>\r\n<\/td>\r\n | \r\n 12<\/p>\r\n<\/td>\r\n | \r\n 11<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n | \r\n \u00a0<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n (c) (i) Define each of the following processes: nuclear fission; nuclear fusion. (d) (i) List three types of radiation that are produced during radioactivity. ANS: <\/strong>(a) (i) Halogens\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Number of neutrons<\/p>\r\n<\/td>\r\n Number of electrons<\/p>\r\n<\/td>\r\n Number of Protons<\/p>\r\n<\/td>\r\n Mass Number<\/p>\r\n<\/td>\r\n<\/tr>\r\n W2+<\/p>\r\n<\/td>\r\n 12<\/p>\r\n<\/td>\r\n 10<\/p>\r\n<\/td>\r\n 12<\/p>\r\n<\/td>\r\n 24<\/p>\r\n<\/td>\r\n<\/tr>\r\n X2-<\/p>\r\n<\/td>\r\n 8<\/p>\r\n<\/td>\r\n 10<\/p>\r\n<\/td>\r\n 8<\/p>\r\n<\/td>\r\n 16<\/p>\r\n<\/td>\r\n<\/tr>\r\n Y<\/p>\r\n<\/td>\r\n 14<\/p>\r\n<\/td>\r\n 13<\/p>\r\n<\/td>\r\n 13<\/p>\r\n<\/td>\r\n 27<\/p>\r\n<\/td>\r\n<\/tr>\r\n Z<\/p>\r\n<\/td>\r\n 12<\/p>\r\n<\/td>\r\n 11<\/p>\r\n<\/td>\r\n 11<\/p>\r\n<\/td>\r\n 23<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n (c)(i) I. Nuclear fission \u2013 splitting of a heavy nucleus into two smaller nuclei of similar mass with the release of a large amount of energy and radiation. 2. (a) (i) What is the structure of the atom as proposed by Rutherford? (b)\u00a0(i) What is meant by first ionization energy? (c)\u00a0Explain\u00a0briefly\u00a0the following terms using an appropriate example in each case (d)\u00a0State the indicator(s) which could be used to determine the end-point of the following titrations: (e) A solid chloride E which sublimed on heating reacted with an alkali F to give a choking gas G. G turned moist red litmus paper blue.\u00a0 Identify E, F and G.<\/p>\r\n ANS:\u00a0<\/strong>(a) (i) The atom has a small\/ tiny positively charged centre \/nucleus with electrons surrounding the space around the centre. \u00a0 (b) (i) Is the (minimum) energy required to remove\u00a0one mole\u00a0of an electron from\u00a0one mole\u00a0of gaseous atom (to form one mole gaseous charged ion (c) (i) Is a family of organic compounds: 3. (a) (i) Define saturated solution.\u00a0 (b) (i) Distinguish between the dative bond and covalent bond.\u00a0 (c) (i) State\u00a0Dalton’s\u00a0Law of Partial Pressure. ANS: <\/strong>(a) (i) Is a solution that contains the maximum amount of solute it can dissolve at a given temperature (in the presence of undissolved solute). (b)(i) In a dative bond, only one of the participating atoms\/ species donated electrons to be shared by both atoms while in a covalent bond both participating atoms\/ species contribute equally to the electrons being shared.\u00a0 (c)(i) the total pressure exerted by a mixture of gases that do not react chemically is equal to the sum of the individual partial pressures of the gases in the mixture. = 685 x 200 x 273\u00a0 = 169.1cm3<\/sup><\/span><\/p>\r\n 4. (a) (i) Define nuclear fission Compound<\/p>\r\n<\/td>\r\n NaF<\/p>\r\n<\/td>\r\n NaBr<\/p>\r\n<\/td>\r\n NaI<\/p>\r\n<\/td>\r\n<\/tr>\r\n \u00a0Lattice energy\/kJmol-1<\/p>\r\n<\/td>\r\n 890<\/p>\r\n<\/td>\r\n 719<\/p>\r\n<\/td>\r\n 670<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n Explain briefly the trend.<\/p>\r\n (d) State the property exhibited by nitrogen (IV) oxide in each of the following reactions: (e) Iron is manufactured in a blast furnace using iron ore (Fe2O3), coke and limestone. 5. Copy and complete the following table:<\/p>\r\n (i) Mention\u00a0one<\/strong>\u00a0compound that makes water 6. (a) (i) What is meant by atomicity? (b) (i) Write a balanced equation for the thermal decomposition of KC\u0196O3. (c) (i) Mention the products formed when\u00a0each\u00a0of the following substances is heated strongly: 7.\u00a0(a) Describe\u00a0briefly\u00a0how\u00a0each\u00a0of the following aqueous solutions could be identified in the laboratory: 8.\u00a0(a)\u00a0 (i) Define standard electrode potential. (c) Classify each of the following oxides as basic, amphoteric, acidic or neutral: (d) What is hydrogen bonding?<\/p>\r\n 9.\u00a0<\/p>\r\n PAPER 1 [Essay]<\/strong> 1.\u00a0Two immiscible liquids with different boiling points can be separated by\u00a0_____ 2. A mixture of CaCl2 and CaCO3 in water can be separated by\u00a0\u00a0______ 3.\u00a0What is responsible for metallic bonding? 4. 25cm3 of 1.5M solution of NaCl are added to 50cm3 of 3M NaCl. The molar concentration of the resulting solution is ________ 5. A solution of salt formed from HCl and NH3 solutions is\u00a0_____ 6. Which of the following elements will burn in excess oxygen to form a product that is neutral to litmus?\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A. carbon\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 B. Hydrogen\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 C. Sulphur\u00a0 \u00a0 \u00a0 \u00a0 D. Sodium<\/p>\r\n 7. A current was passed for 10 mins and 0.2mole of Cu was deposited. How many grammes of Ag will it deposit? 8. Pollution of underground water by metal ions is very likely in a soil that has high\u00a0\u00a0________ 9. Producer gas is a gas with low caloric value because it contains more\u00a0____ 10.\u00a0Silver chloride turns grey when exposed to sunlight because _____ 11. Which of these compounds exhibits resonance? 15. Hydrolysis of CH3COOCH2CH3 in dilute HCl produces ______ 16.\u00a0Calculate the volume of CO2 measured at s.t.p produced on heating 250g of potassium hydrogen trioxocarbonate (IV) strongly. 17. The boiling points of water, ethanol, methylbenzene and butan-2-ol are 373.0K, 351.3K, 383.6K and 372.5K respectively. Which liquid has the highest vapour pressure at 323.0K? 18. The conclusion from Rutherford\u2019s alpha scattering experiment is that\u00a0______ 19. Elements P, Q and R have atomic numbers 9, 16 and 20 respectively. Which of them would gain electron(s) during ionic bonding\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 A. Q and R 20. Which of the following has the lowest PH? 21. Which of the following is an acid salt? 22. Cr2O2-7 + 14H+\u00a0 + 6I \u2192 2Cr3+\u00a0 + 3I2\u00a0 + 7H2O. The change in the oxidation number of oxygen in the equation above is _______ 23. During electrolysis of CuSO4 solution using platinum electrodes, which of the following occurs\u00a0______ 24. Which of the following ions is a pollutant in drinking water even in trace quantities? 25.\u00a0The solubility of a salt of molar mass 100g at 20oC is 0.34mol\/dm3. If 3.4g of that\u00a0salt dissolved completely 250cm3 of water at that temperature, the resulting solution is ________ 26. Catalyst is important in in chemical industry in that\u00a0______ 27. An alkanioc acid has a molecular mass of 88. Name the acid. 28. Ethyne undergoes the following reactions EXCEPT 29.\u00a0<\/p>\r\n Keep following, more questions and answers will be added soon.<\/strong><\/p>\r\n PS:<\/strong> Once again, there is nothing like waec chemistry expo. Do not fall victim to scammers online trying to obtain money from you with fake promises of having access to live question paper before the exam. What we have on this page are likely exam questions from waec past questions and answers to serve as a revision guide.<\/p>\r\n |