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WAEC Chemistry Trial Questions
WAEC March 13, 2020 • 11 months ago • No Comment Yet


Chemistry Trial Questions
1. Identify the solid remaining when each of the following is heated.
(a) lithium trioxonitrate (V);
(b) potassium trioxonitrate (V);
(c) calcium trioxonitrate (V);
[3 marks]
2. (a) When calcium oxide and coke are heated in a electric furnace, the
products are carbon (ii) oxide and calcium carbide (CaC2), write the equation
for this reaction. [2 marks]
(b) Addition of water to calcium carbide leads to the formation of calcium
and ethyne. Write the equation for the production of ethyne. [2 marks]
3. Calculate the percentage by mass of silicon tetrachloride. [2 marks]
4. Ammonia, NH3, and phosphine, Ph3, are the hydrides of the first two
elements in group 5.
(a) Draw a dot and cross diagram for the ammonia molecule. [2 marks]
(b) Sketch and explain the shape of the ammonia molecule. [3 marks]
5. The first ionization energy of chlorine is +1260KJmol-1.
(a) Define the term first ionization energy. [2 marks]
(b) State and explain the general trend in the values of the first ionization
energy for the elements across the period, sodium to argon in the periodic
table.[3 marks]
6. Compound A consisting of carbon and hydrogen only. The compound was
found to contain 80% carbon by mass.
(a) Calculate the empirical formula of compound A using the data above. [3
(b) The relative molecular mass of compound A was found to be 30.
Use this information to deduce the molecular formula of compound A. [H =
1.00 C = 12.00] [3 marks]
7. State two factors other than a change in temperature or the use of a
catalyst that influence the rate of a chemical reaction. [2 marks]
1. (a) Two elements represented by the letters Q and R have atomic numbers
9 and 12 respectively.
(i) Write the election configuration of R.
(ii) To what group does Q belong in the periodic table.
(iii) Write the formula of the compound formed when Q combines with R.
(iv) Explain briefly, why Q is a good oxidizing agent.
(v) State whether R would be expected to form acidic or basic oxide. [ 25
(b) (i) State two assumptions of the kinetic theory of gases.
(ii) When some solids are heated, they change directly into the gaseous state.
What name is given to this phenomenon?
(iii) List two substances which exhibit the phenomenon mentioned in (ii).
(iv) Write an expression to show the mathematical relationship between
the rate of diffusion of a gas and its vapour.
[25 marks]
2. An aqueous solution has a pH of 4.0.
(a) (i) What is the hydrogen ion concentration of the solution?
(ii) What effect will it have on litmus paper?
(iii) Which of the following salt solutions would have the same effect on
litmus? Give a reason for your answer.
NH4Cl(aq); NaCl(aq); CH3(OONa(aq).
(b) (i) Differentiate between a fine chemical and a heavy chemical.
(ii) Name two sources of air pollution.
(iii) Suggest one way of reducing air pollution in cities.
[ 25 marks]
3. (a) (i) Explain briefly the fermentation process.
(ii) Write a balanced equation for the fermentation of glucose.
(iii) What substance must be added to glucose solution to ferment it?
(iv) Explain briefly why tightly corked glass filled to the brim with palm
wine shatters on standing.
(b) State one industrial application of each of the following methods
of separation:
(i) crystallization;
(ii) fractional distillation.
(c ) Explain the following terms:
(i) saponification;
(ii) esterification.
(d) Write a balanced equation to illustrate each of the terms in (c).
(e) (i) What is hydrocarbon compound?
(ii) Name two principal sources of hydrocarbons.
[25 marks]
1. A is a solution of HCl of unknown concentration.
B contains 1.00g of NaOH in 250cm3 of solution.
(a) Put A into the burette and titrate it against 20.0cm3 or 25.0cm3 portions
of B using methyl orange as indicator.
Tabulate your burette readings and calculate the average volume of A used.
The equation for the reaction involved in the titration is
NaOH + HCl  NaCl + H2O
(b) From your results and the information provided above, calculate the
(i) concentration of A in moldm-3;
(ii) concentration of A in gdm-3.
[H=1.0;O=16; Na=23;Cl=35.5]
2. C is a solution of a simple salt. Carry out the following exercises on C.
Record your observations and identify any gases evolved.
State the conclusions you draw from the result of each test.
Put about 2cm3 each of C in three separate test tubes.
(a) To the first portion of C add NaOH(aq) in drops and then in excess.
(b) To the second portion of C add a few drops of AgNO3(aq) followed by
excess HNO3(aq).
(c) To the third portion of C add about 2cm3 of KI(aq).
3. State the apparatus that could be used to
(i) separate liquids whose boiling points are within a range of five
(ii) change vapour into liquid during distillation;
(iii) separate a mixture of starch and water.
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DISCLAIMER: The questions contained on this website are not in any way inferred as the original questions you will write on your WASSCE.
The contents on this website are purely educational and suited for students preparing for the said exams.


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