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 1711–1725 of 4783 verified questions
Sort by:
Chemistry
WAEC / WASSCE 2012
Acids, Bases, and Salts
Solution
The complex compound formed when aluminum dissolves in aqueous sodium hydroxide is
A
Na3Al(OH)4.
B
NaAl(OH)4
C
NaAl(OH)3
D
Na2Al(OH)3
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
When aluminium is treated with dilute sodium hydroxide it forms a salt called sodium tetrahydroxoaluminate and hydrogen gas.
Source: Myschool Past Questions Archive (Record #37752)
Chemistry
WAEC / WASSCE 2012
Stoichiometry & Mole Concept
Solution
The vapour pressure of a liquid depends on l. temperature. ll. rate of condensation. III. cohesive forces holding the particles together
A
l only
B
l and ll only
C
l and lll only
D
ll and lll only
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Three common factors that influence the vapor pressure of a liquid are the surface area, intermolecular forces and the temperature.
Source: Myschool Past Questions Archive (Record #37753)
Chemistry
WAEC / WASSCE 2012
Matter & Separation Techniques
MgO does not readily dissolve in water because
A
of its high melting point
B
it is a covalent compound
C
it forms a hydroxide when dissolved in water
D
its lattice energy is higher than its hydration energy
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 #37754)
Chemistry
WAEC / WASSCE 2012
Stoichiometry & Mole Concept
Solution
Consider the following reaction equation: CaCO\(_{3(s)}\) + 2HCI\(_{(aq)}\) → CaCl\(_{2(aq)}\) + H\(_2\)O\(_{(l)}\) + CO\(_{2(g)}\). What mass of CaCI\(_2\) would be obtained when 25.0g of CaCO\(_{3(s)}\) is reacted with excess HCI\(_{(aq)}\)? [CaCO\(_3 = 100; CaCI\(_2\) = 111]
A
4.00g
B
4.44 g
C
18.9 g
D
27.8 g
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
CaCO\(_3\) + 2HCI → CaCI\(_2\) + H\(_2\)O + CO\(_2\)
100g CaCO\(_3\) will produce 111g CaCI\(_2\)
25g CaCO\(_3\) will produce x ,
x = \(\frac{25 x 111}{100}\)
= 27.75 \(\approxeq\) 27.8g
Source: Myschool Past Questions Archive (Record #37755)
Chemistry
WAEC / WASSCE 2012
Matter & Separation Techniques
Solution
Which of the following metals would readily displace hydrogen from steam?
A
Copper
B
Lead
C
Magnesium
D
Silver
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
In the electrochemical series, H\(^+\) is above all the other elements in the series except Magnesium. Hence, only Mg\(^{2+}\) can displace hydrogen from a reaction.
Source: Myschool Past Questions Archive (Record #37769)
Chemistry
WAEC / WASSCE 2012
Stoichiometry & Mole Concept
Solution
The volume occupied by 0.4 g of hydrogen gas at s.t.p. is [H = 1. 00; Molar volume at s.t.p. = 22.4 dm3]
A
2.24 dm3
B
4.48dm3
C
22.4dm3
D
44.8dm 3
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
2g of H\(_2\) = 22.4 dm\(^3\)
0.4g of H\(_2\) = x,
x = \(\frac{0.4 \times 22.4}{2}\) = 4.48dm\(^3\)
Source: Myschool Past Questions Archive (Record #37770)
Chemistry
WAEC / WASSCE 2012
Matter & Separation Techniques
When a substance changes directly from the solid state to the gaseous state without forming a liquid, the substance is said to
A
condense
B
evaporate
C
sublime
D
precipitate
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 #37771)
Chemistry
WAEC / WASSCE 2012
Atomic Structure and Periodic Table
Solution
At ordinary temperature H\(_2\)O is a liquid while H\(_2\)S is a gas. This is because H\(_2\)O has
A
weak intermolecular forces holding its molecules together
B
strong hydrogen bonds holding its molecules together
C
induced dipole-induced dipole forces between its molecules
D
ionic force between its molecules
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
H\(_2\)O has stronger intermolecular dipole--dipole interaction because of the greater polarity (or a hydrogen bond). Because of the stronger intermolecular interaction H\(_2\)O is more stable and exists as a liquid.
Source: Myschool Past Questions Archive (Record #37772)
Chemistry
WAEC / WASSCE 2012
Stoichiometry & Mole Concept
Solution
The postulate that molecules are in constant random motion best explains why liquids
A
can undergo solidification
B
maintain their volumes
C
are incompressible
D
have no characteristic shape
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The postulate best explains why liquids take their shape of their container and don't have a fixed characteristic shape because the molecules are free to move and flow, allowing the liquid to change shape in response to the container.
Source: Myschool Past Questions Archive (Record #37773)
Chemistry
WAEC / WASSCE 2012
Stoichiometry & Mole Concept
Solution
Which of the following gases has the lowest rate of diffusion under the same condition? [H = 1.00; He = 4. 00; O = 16.0; CI = 35.5]
A
CI2
B
H2
C
He
D
O2
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
According to Graham's law of diffusion and effusion,
r \(\propto\) \(\sqrt{\frac{1}{M}}\).
Therefore, the more the molar mass, the less the rate of diffusion and effusion.
Source: Myschool Past Questions Archive (Record #37774)
Chemistry
WAEC / WASSCE 2012
Kinetics, Energetics and Equilibrium
Solution
The energy evolved when magnesium burns in air is in the form of
A
heat
B
heat and sound
C
light and heat
D
sound
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
When a piece of magnesium ribbon is ignited, light and heat are produced.The reaction is an exothermic reaction, as well as one that produces light energy.
Source: Myschool Past Questions Archive (Record #37775)
Chemistry
WAEC / WASSCE 2012
Matter & Separation Techniques
Solution
A substance L reacts with NH\(_4\)NO\(_{3(aq)}\) to generate ammonia gas. L is likely to be
A
HCl
B
NaOH
C
CH3COOH
D
CaSO4
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The reaction between NH\(_4\)NO\(_{3(aq)}\) and any metal hydroxide produces ammonia, water and an alkali metal nitrate.
Source: Myschool Past Questions Archive (Record #37780)
Chemistry
WAEC / WASSCE 2012
Acids, Bases, and Salts
Solution
On heating, the following trioxocarbonate (IV) salts decompose to give solid residue except
A
ammonium trioxocarbonate (IV)
B
calcium trioxocarbonate (IV)
C
lead (ll) trioxocarbonate(IV)
D
zinc trioxocarbonate (IV)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Ammonium trioxocarbonate (IV) is an unstable compound. It decomposes on heating to yield ammonia, carbon (IV) oxide and water. All of these are gases.
Source: Myschool Past Questions Archive (Record #37781)
Chemistry
WAEC / WASSCE 2012
Acids, Bases, and Salts
Which of the following pH values indicates that a solution is a strong base?
A
1
B
5
C
9
D
13
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 #37782)
Chemistry
WAEC / WASSCE 2012
Acids, Bases, and Salts
Solution
The hydrolysis of NH\(_4\)CI gives
A
an acidic solution
B
an alkaline solution
C
a buffer solution
D
a neutral solution
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
When you dissolve ammonium chloride crystals in water (H\(_2\)O), the ammonium chloride compound decomposes into its component ions: NH\(_4 ^+\) and Cl\(^-\). The reaction of these ions with water gives an acidic solution.
Source: Myschool Past Questions Archive (Record #37789)