WAEC 2025 Chemistry | Essay

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Question 1 View Details
Answer all the questions in this section.
Question Parts
(a)
How many moles are there in 4.8 g of ozone? \( [O=16.0] \)
(b)
Write the formula for each of the following ions:
(c)
Name the following organic compounds:
(d)
Explain briefly the statement an atom is electrically neutral?
(e)
Write electron configuration for each of the following:
(f)
What is an acid salt?
(g)
An element is represented as \( { }_{b}^{a} \mathrm{X} \), where \( X \) is the symbol of the element. What do the letters \( a \) and \( b \) represents?
(h)
What separation method could be used to separate a mixture of:
(i)
State the type of bonding that occurs in each of the following species;
(j)
Arrange the following metals in order of increasing reactivity: Pb; Zn; Mg; Na; Ag.
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Question 2 View Details
Answer all the questions in this section.
Question Parts
(a)
Explain briefly each of the following terms.
(b)
Complete the following table:
(c)
State the type of reaction illustrated in each of the following equations:
(d)
Name two strong inorganic acids.
(e)
Calculate the volume of \( 0.10 \mathrm{~mol} d m^{-3} \) KOH required to neutralize \( 12.50 \mathrm{~cm}^{3} \) of 0.10 mold \( d m^{-3} \mathrm{H}_{8} \mathrm{SO}_{4} \).
(f)
Define the term electrolysis.
(g)
Explain the effect of concentration on the anion that is preferentially discharged in the electrolysis of brine.
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Question 3 View Details
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Question Parts
(a)
Consider the following elements: Na; Cl; Ca and O.
(b)
When drops of compound X are added to calcium oxide, compound Y is produced. Y reacts with ammonium chloride on heating to produce gas Z which turns damp red litmus paper blue.
(c)
Write a balanced equation for the reaction of aluminium with oxygen.
(d)
What mass of oxygen would react with 9.0 g of aluminium? [ \( \mathrm{O}=16.0 \), \( ext{AI} =27.0 \)]
(e)
Name the element that is added to natural rubber to improve its quality.
(f)
What is a disproportionation reaction?
(g)
Give the oxidation state of phosphorus in each of the following species:
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Question 4 View Details
Answer all the questions in this section.
Question Parts
(a)
State Dalton's law of partial pressure.
(b)
A cylinder contains 2 moles of \( \mathrm{O}_{2}, 3 \) mole of \( \mathrm{CO}_{2} \) and 5 moles of \( \mathrm{N}_{2} \) at a particular temperature. If the pressure in the cylinder is \( 210 \mathrm{Nm}^{-2} \), calculate the partial pressure of \( \mathrm{O}_{2} \) and \( \mathrm{N}_{2} \).
(c)
Define the term concentration of a solution.
(d)
Calculate the mass concentration of \( 0.10 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{Na}_{2} \mathrm{CO}_{3} \left[\mathrm{Na}_{2} \mathrm{CO}_{3}=106\right] \).
(e)
Describe how a \( 1 \, ext{dm}^{3} \) solution of 0.1 mol \( d m^{-3} \mathrm{Na}_{2} \mathrm{CO}_{3} \) could be prepared.
(f)
State two physical properties of each of the following substances: Chlorine; Hydrogen chloride.
(g)
State what would be observed when burning splint of hydrogen is introduced into a gas jar containing chlorine.
(h)
Consider the following gases: \( \mathrm{CO}_{2} ; \mathrm{HCl} \) and \( \mathrm{CH}_{4} \).
(i)
State one industrial use of hydrogen chloride gas.
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Question 5 View Details
Answer all the questions in this section.
Question Parts
(a)
When air reacts with red hot coke, a fuel is formed.
(b)
Write an equation for the reaction between sodium and water.
(c)
Write the equation(s) for the main reaction of Iron (III) oxide in the blast furnace.
(d)
Explain briefly why the temperature in the blast furnace decreases from bottom to top.
(e)
The table below shows the products of the destructive distillation of coal and their uses. Study and complete the table.
(f)
Mention one industrial process in which each of the following compounds are used.
(g)
State the function of each of the compounds in 5(d)(i) in the industrial process.
(h)
Name the compound \( ext{KAl} \left( ext{SO}_{4} ight)_{2} \).
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