Question Library
Browse, filter, and study verified past examination questions with step-by-step mathematical reasoning.
Searching 18,000+ Questions...
Sifting topics, KaTeX formulas & verified solutions
Showing 2176–2190 of 4783 verified questions
Sort by:
Chemistry
WAEC / WASSCE 2008
Stoichiometry & Mole Concept
What is the mass of 6.02 x 1024 atoms of magnesium? [Mg = 24, Avogadro constant = 6.02 x 1023 atoms mol-1]
A
240g
B
24 g
C
2.4g
D
0.24g
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 #37275)
Chemistry
WAEC / WASSCE 2008
Stoichiometry & Mole Concept
Which of the following compounds with the corresponding masses contain the highest percentage of nitrogen? [N = 14]
A
NH3 = 17
B
NH4CI = 53.5
C
NH4NO3 = 80
D
(NH3)2SO4 = 132
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 #37276)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
Solution
If 5.00cm3 of 0.20 mol dm-3Na2CO3 was diluted with distilled water to obtain 250 cm3 solution, what is the concentration of the resulting solution?
A
0.004 mol dm-3
B
0.02 mol dm-3
C
0.20mol dm-3
D
0.40mol dm-3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
This problem can be solved by using the standard dilution formula:
C\(_1\)V\(_1\) = C\(_2\)V\(_2\)
C\(_1\) = 0.20 moldm\(^{-3}\)
V\(_1\) = 5.0 cm\(^3\)
C\(_2\) = ?
V\(_2\) = 250 cm\(^3\)
C\(_2\) = \(\frac{C_1V_1}{V_2}\)
= \(\frac{0.20 x 5.0}{250}\)
= 0.004 moldm\(^{-3}\)
Source: Myschool Past Questions Archive (Record #37278)
Chemistry
WAEC / WASSCE 2008
Stoichiometry & Mole Concept
Consider the reaction represented by the following equation: Zn(s) + 2HCI(aq) → ZnCI2(aq) + H2(g) what volume of hydrogen gas is produced at s.t.p. when 3.25 g of zinc reacts with excess dilute HCI? [Zn = 65, Molar gas volume at s.t.p. = 22.4 dm-3]
A
1.12 dm3
B
2.24dm3
C
4.48dm3
D
8.96dm3
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 #37279)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
Which of the following gases has the lowerst rate of diffusion under the same conditions of temperature and pressure? [H = 1, O = 16, Ne = 20, CI = 35]
A
Chlorine
B
Hydrogen
C
Neon
D
Oxygen
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 #37280)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
In a fixed volume of a gas, an increase in temperature results in an increase in pressure due to an increase in the
A
number of the collisions between the gas molecules and the walls of the container
B
kinetic energy of the gas
C
number of collisions between the gas molecules
D
number of repulsion between the gas molecules
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 #37281)
Chemistry
WAEC / WASSCE 2008
Acids, Bases, and Salts
Solution
When concentrated \(H_2SO_4\) is added to NaCI (s), the gas evolved
A
bleaches damp blue litmus paper
B
forms a white preciptate with AgNO3(aq)
C
forms a white precipitate with BaCI2(aq)
D
turns moist red litmus paper blue
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
2\(NaCl_{(aq)} + H_2SO_{4(aq)} → Na_2SO_{4(aq)} + 2HCl_{(g)}\)
This gas(hydrochloride gas) turns damp/moist blue litmus paper red while reacting with \(AgNO_{3(aq)}\), a white precipitate of AgCl is produced which is soluble in ammonia solution but insoluble in \(HNO_3\)
Source: Myschool Past Questions Archive (Record #37282)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
The collision theory proposes that
A
reactants collide more frequently to bring about reduction in the reaction rate
B
all collisions of reactants are effective
C
reactants must collide with a certain minimum amount of energy to from products
D
the fewer the collisions the faster the reaction rate
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 #37283)
Chemistry
WAEC / WASSCE 2008
Kinetics, Energetics and Equilibrium
Which of the following set of equations could be used to represent the standard enthalpy of formation of glucose?
A
6C (s) + 6H 2(g) + 3O2(g) → C 6H12O6(s)
B
6CO2(g) + 6H2O (l) → C6H12O6(s) + 6O 2(g)
C
6C(g) + 6H 2(g) + 3O2(g) → C6H12O 6(s)
D
6C(g) + 6H 2(g) + 3O2(g) → C 6H 12O 6(aq)
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 #37285)
Chemistry
WAEC / WASSCE 2008
Acids, Bases, and Salts
The colour of phenolphthalein indicator in dilute HNO is
A
colourless
B
orange
C
pink
D
purple
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 #37286)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
An aqueous solution of CaCI2 is
A
acidic solution
B
alkaline solution
C
a buffer solution
D
a neutral solution
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 #37287)
Chemistry
WAEC / WASSCE 2008
Acids, Bases, and Salts
Solution
Which of the following compounds would dissolved in water to give a solution whose pH is less than 7?
A
AI(NO3)3
B
KNO3
C
N2O
D
NH3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Aluminum nitrate (Al(NO3)3) is a salt that dissolves in water to produce hydrogen ions (H\(^+\)), which are acidic:
Al(NO\(_3\))\(_3\) → Al\(^{3+}\) + 3NO\(_3\)\(^-\)
Al\(^{3+}\) + 3H\(^2\)O → Al(OH)\(_3\) + 3H\(^+\)
The released hydrogen ions (H\(^+\)) increase the acidity of the solution, resulting in a pH less than 7.
The other options:
B. Potassium nitrate (KNO\(_3\)) is a neutral salt and does not affect the pH.
C. Nitrous oxide (N\(^2\)O) is a gas and does not dissolve in water to affect pH.
D. Ammonia (NH\(_3\)) is a base and would increase the pH of the solution (make it more alkaline).
So, aluminum nitrate (Al(NO3)3) is the correct answer.
Source: Myschool Past Questions Archive (Record #37288)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
Consider the reaction represented by the question below: KOH(aq) + HCI(aq) → KCI(aq) + H2O(l) What volume of 0.25 mol dm-3 KOH would be required to completely neutralize 40 cm3 of 0.10 mol dm -3 HCI?
A
40 cm3
B
32cm3
C
24cm3
D
16cm3
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 #37289)
Chemistry
WAEC / WASSCE 2008
Acids, Bases, and Salts
When 100 cm3 of a saturated solution of KCIO3 at 40oC is evaporated, 14 g of the salt is recovered what is the solubility of KCIO3 at 40oC? [KCIO3 = 122.5]
A
11.42 mol dm-3
B
8.80 mol dm-3
C
1. 14 mol dm-3
D
0.88 mol dm-3
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 #37290)
Chemistry
WAEC / WASSCE 2008
Matter & Separation Techniques
The high solubility of ethanol in water is due to its
A
low boiling point
B
low freezing point
C
covalent nature
D
hydrogen bonding
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 #37291)