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Chemistry
WAEC / WASSCE 1989
Acids, Bases, pH & Salts
Which of the following gases will bleach moist litmus paper?
A
CI2
B
CO2
C
SO2
D
HCI2
E
N2 O
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #36066)
Chemistry
WAEC / WASSCE 1989
Acids, Bases, pH & Salts
Solution
Given that for the reaction KOH (aq) + HCI(aq) → KCI(aq) + H2O(L) H = - 54 Kj mol-1. What is the quantity of heat involved in the reaction?2NaOH(aq) + H2SO 4(aq) → Na2SO4(aq) + 2H 2O(l)?
A
- 108Kj
B
-54 kj
C
-27 kj
D
+27 kj
E
+54 kj
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Given that \(KOH_{(aq)} + HCl_{(aq)} \to KCl_{(aq)} + H_{2}O_{(l)} ; \Delta H = -54 kJ/mol\)
The standard heat of neutralization is the amount of heat evolved when 1 mole of hydrogen ion from an acid reacts with 1 mole of hydroxide ion from the base to form one mole of water, under standard conditions.
\(\therefore 2NaOH_{(aq)} + H_{2}SO_{4(aq)} \to Na_{2}SO_{4(aq)} + 2H_{2}O_{(l)} ; \Delta H = -(2 \times 54 kjmol^{-1})\)
\(\therefore \Delta H = -108 kJmol^{-1}\)
Source: Myschool Past Questions Archive (Record #36067)
Chemistry
WAEC / WASSCE 1989
Non-Metals & Their Compounds
Solution
When an element can exist in two or more forms in the same physical state, the element is said to exhibit
A
isotopy
B
isomerism
C
allotropy
D
hygroscopy
E
sublimation
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Allotropy refers to the existence of an element in two or more different forms in the same physical state, such as carbon existing as both graphite and diamond.
Source: Myschool Past Questions Archive (Record #36068)
Chemistry
WAEC / WASSCE 1989
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Which of the following carbohydrates does NOT usually occur in the crystalline form?
A
Fructose
B
Glucose
C
Sucrose
D
Maltose
E
Cellulose
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36069)
Chemistry
WAEC / WASSCE 1989
Nature of Matter & Separation Techniques
Copper can best be purified by
A
roasting the impure copper in a blast furnace
B
heating the oxide with coke
C
electrolyzing a copper (ll) salt solution using the impure copper as the anode
D
converting the impure copper to a trioxonitrate (V)
E
washing the impure copper with sodium hydroxide solution
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #36070)
Chemistry
WAEC / WASSCE 1989
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Locally produced soap in which wood ash is used as the base is usually soft because the wood ash contains a lot of
A
sodium ions
B
potassium ions
C
lithium ions
D
calcium ions
E
magnesium ions
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #36071)
Chemistry
WAEC / WASSCE 1989
Electrolysis & Electrochemical Cells
Why is potassium fluoride added to the electrolyte in the extraction of sodium from fused sodium chloride?
A
Pure sodium chloride does not conduct electricity
B
Potassium fluoride prevents the sodium produced from attacking the electrodes
C
Potassium fluride increases conductivity
D
Potassium fluride reduces the temperature at which sodium chloride fuses
E
the potassium fluride acts as a catalyst
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #36072)
Chemistry
WAEC / WASSCE 1989
Metals, Transition Elements & Extraction
The rate of the hydrogen in the reaction Zn(s) + 2HCI (aq) → ZnCI 2(g) + H 2(aq) + H 2(g) can be increased by
A
using Zinc powder instead of Zinc granules
B
using dilute instead of concentrated hydrochloric acid
C
cooling the container in which the mixture is placed
D
using an alloy of zinc instead of pure zinc
E
using hydrogen chloride gas instead of hydrochloric acid solution
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #36073)
Chemistry
WAEC / WASSCE 1989
Organic Chemistry I: Hydrocarbons & Crude Oil
Octane number is highest in petrol containing a high proportion of
A
heptane
B
octane
C
2-methylpentane
D
2, 4-dimethylpentane
E
2,2,4-trimethylpentane
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36074)
Chemistry
WAEC / WASSCE 1989
Stoichiometry, Mole Concept & Volumetric Analysis
Given the following half-cell reaction; 2Cl(aq) → CI2(g) + 2e, how many mole of electrons will be required to produce 1.12dm3 of chlorine gas at s.t.p? (Molar volume of a gas at s.t.p. = 22.4dm 3)
A
1.00
B
0.40
C
0.20
D
0.10
E
0.01
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #36075)
Chemistry
WAEC / WASSCE 1989
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following is used extensively in manufacturing photographic chemicals?
A
Aluminium chloride
B
Zinc chloride
C
Silver chloride
D
Mercury (ll) chloride
E
lron (ll) chloride
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #36076)
Chemistry
WAEC / WASSCE 1989
Stoichiometry, Mole Concept & Volumetric Analysis
Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)
A
1/2 x 6.02 x 10 23
B
1 x 6.02 x10 23
C
2 x 6.02 x 10 23
D
3x 6.02 x 10 23
E
4x 6.02 x 10 23
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #36077)
Chemistry
WAEC / WASSCE 1989
Non-Metals & Their Compounds
Solution
If sulphur is dissolved in carbon (IV) sulphide and the solution allowed to evaporate the allotrope of sulphur formed is
A
plastic sulphur
B
amorphous sulphur
C
rhombic sulphur
D
monoclinc sulphur
E
colloidal sulphur
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
rhombic Sulphur is prepared by allowing a saturated solution of Sulphur in carbon (iv) sulphide to evaporate slowly and crystals will gradually be deposited.
Source: Myschool Past Questions Archive (Record #36078)
Chemistry
WAEC / WASSCE 1989
Non-Metals & Their Compounds
If sulphur is dissolved in carbon (IV) sulphide and the solution is allowed to evaporate, the allotrope of sulphur formed is
A
plastic sulphur
B
amorphous sulphur
C
rhombic sulphur
D
monoclinc sulphur
E
colloidal sulphur
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #36079)
Chemistry
WAEC / WASSCE 1989
Chemical Energetics & Thermochemistry
Solution
Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H = -92kJ. What is the enthalpy of formation of ammonia from its elements?
A
-46KJ mol -1
B
-184KJmol -1
C
-92KJmol -1
D
184KJmol -1
E
+46KJmol -1
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
In the reaction the enthalpy of formation 2 mole of NH3 is - 92kJ. Therefore the standard \(\Delta H\) of formation = \(\frac{-92kJ}{2} = -46KJmol^{-1}\).
Source: Myschool Past Questions Archive (Record #36080)