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 1606–1620 of 4783 verified questions
Sort by:
Chemistry
WAEC / WASSCE 2013
Stoichiometry & Mole Concept
Solution
The volume of 0.25 moldm-3 solution of KOH that would yield 6.5g of of solid KOH on evaporation is (K = 39.0; o = 16.0; H = 1.00)
A
464.30 cm3
B
625.00 cm3
C
1000.00 cm3
D
2153.80 cm3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
number of moles = molar concentration x volume(\(dm^3\))
molar concentration(C) = 0.25mol/dm3, volume = ? and number of mole(n) = \(\frac{mass}{molar mass}\) = \(\frac{6.5}{56}\) ( where 56g/mol = molar mass of KOH)
\(\frac{6.5}{56}\) = 0.25 x V
V = \(\frac{0.11607}{0.25}\) = 0.46428dm^3 → 464.3cm^3
Source: Myschool Past Questions Archive (Record #37681)
Chemistry
WAEC / WASSCE 2013
Stoichiometry & Mole Concept
Solution
The percentage by mass of calcium in Ca(OCI)2 is [Ca = 40.0; CI = 35.5; O = 16.0]
A
28.0%
B
31.6%
C
43.8%
D
44.5%
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Molar mass of \(Ca(OCl)_2\) = 40 + (16 + 35.5)x2 = 143
% by mass of calcium in the compound =\(\frac{mass of calcuim}{molar mass of compound}\) x 100%
% calcium = \(\frac{40}{143} \times100\)
= 27.98% = 28%
Source: Myschool Past Questions Archive (Record #37682)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
The gas law which describes the relationship between volume and temperature is
A
Boyle's law
B
Charles' law
C
Dalton's law
D
Graham's law
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 #37683)
Chemistry
WAEC / WASSCE 2013
Acids, Bases, and Salts
Which of the following phenomenna lead to decrease in volume of a liquid in an open container?
A
Brownian motion
B
Diffusion
C
Evaporation
D
Sublimation
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 #37684)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
The pressure exerted by a gas is a function of the
A
total volume of the gas
B
speed of the gaseous molecules
C
mass of each gaseous molecule
D
frequency of collision between gaseous molecules
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 #37685)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
Which of the following gases are arranged in increasing order of diffusion rate? [H = 1 .0; C = 12; N = 14; O = 16; S = 32]
A
SO 2 O2, NH3 H2
B
H2S,NH2,O2,SO2
C
CO2,N2O,O2,SO2
D
NH3,NO2,N2,CO2
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 #37686)
Chemistry
WAEC / WASSCE 2013
Stoichiometry & Mole Concept
Which of the following variables is a measure of the average kinetic energy of the molecule of a gas?
A
Density
B
Pressure
C
Temperature
D
Volume
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 #37687)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
When heat is absorbed during a chemical reaction, the reaction is said to be
A
adiabatic
B
endothermic
C
exothermic
D
isothermal
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 #37688)
Chemistry
WAEC / WASSCE 2013
Acids, Bases, and Salts
The aqueous solution which has pH > 7 is
A
FeCI3(aq)
B
CuSO4(aq)
C
KNO3(aq)
D
Na2CO3(aq)
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 #37689)
Chemistry
WAEC / WASSCE 2013
Acids, Bases, and Salts
Solution
Which of the following acids would readily react with CaCO3 to liberate CO2?
A
CH3COOH
B
H2SO4
C
H2SO3
D
HNO3
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
H2SO4(aq)+CaCO3(aq)→CaSO4(aq)+CO2(g)+H2O(l)
Source: Myschool Past Questions Archive (Record #37690)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
Which of the following compounds crystallizes without water of crystallization?
A
MgSO4
B
Na2CO3
C
NaCI
D
FeSO4
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 #37691)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
A substance is said to be impure if
A
its melting point range is wide
B
it dissolves in water with difficult
C
it has a low melting point
D
it is coloured
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 #37692)
Chemistry
WAEC / WASSCE 2013
Matter & Separation Techniques
The following factors affect the solubility of a solid in a given solvent except
A
nature of solute
B
nature of solvent
C
pressure
D
temperature
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 #37693)
Chemistry
WAEC / WASSCE 2013
Kinetics, Energetics and Equilibrium
Solution
Consider the reaction represented by the equation: N\(_2\)O\(_4\)(g) ⇌ 2NO\(_2\)(g) ; ∆H = + x kJmol-1
What happens when the temperature is reduced at equilibrium?
A
Concentration of N 2O4(g) decreases
B
Concentration of N 2O4(g) increases.
C
Pressure exerted by the gases increases
D
Pressure exerted by the gases remains constant
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
According to Le Chatelier's principle, in an endothermic reaction(\DeltaH = +ve), an increase in temperature will cause the equilibrium to shift to the right, thereby favouring the forward reaction, and more product will be formed. Conversely, in an endothermic reaction, a decrease in temperature will cause the equilibrium position to shift to the left, thereby favouring the backward reaction, and more reactants(N\(_2\)O\(_4\)) will be produced.i.e Concentration of N\(_2\)O\(_4\) will increase.
Source: Myschool Past Questions Archive (Record #37694)
Chemistry
WAEC / WASSCE 2013
Acids, Bases, and Salts
Which of the following cells produce electrical energy from chemical reactions?
l. Lead-acid battery ll. Dry cell III. Deniell cell IV Electrolytic cell
A
l and ll only
B
l, ll, and III only
C
lll and IV only
D
I and III only
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 #37695)