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Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
The high solubility of ethanol in water is due to?
A
its low boiling point.
B
its low freezing point.
C
its covalent nature
D
hydrogen bonding
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Ethanol is an alcohol that is soluble in water. This is because of the hydroxyl group (−OH) in the ethanol that is able to form hydrogen bonds with the water (H2O) molecules.
Source: Myschool Past Questions Archive (Record #58799)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
Which of the following pairs of properties of alkali metals decreases down the group?
A
First ionization energy and reactivity
B
melting point and atomic radius
C
Reactivity and electronegativity
D
First ionization energy and melting point
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
- The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:
- It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge.
- The ionization energy decreases from top to bottom in groups, and increases from left to right across a period.
- The boiling and melting points decrease as you move down the group.
Source: Myschool Past Questions Archive (Record #58803)
Chemistry
WAEC / WASSCE 2020
Matter & Separation Techniques
Solution
The most suitable process of obtaining water from an aqueous solution of sugar i
A
Crystallization
B
Distillation
C
Filtration
D
Decantation
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
- Crystallization is primarily employed as a separation technique to obtain pure crystals of a substance from an impure mixture.
- Another important application of crystallization is its use to obtain pure salt from seawater.
- Simple syrup crystallizes when enough of the sugar molecules stick to one another that they become insoluble in the water
note; distillation is used to obtain a solvent from a solution.
Source: Myschool Past Questions Archive (Record #58816)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
When an ionic bond is broken, bonding electrons are
A
shared between participating atoms
B
gained by the most electropositive atom
C
gained by the most electronegative atom
D
lost by both participating atoms.
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 #58825)
Chemistry
WAEC / WASSCE 2020
Electrochemistry and Redox
Solution
The oxidation state of chlorine in NaClO\(_3\) is?
A
+1
B
+3
C
+5
D
+6
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
the oxidation number of chlorine in NaClO3 is +5.
Source: Myschool Past Questions Archive (Record #58839)
Chemistry
WAEC / WASSCE 2020
Stoichiometry & Mole Concept
Solution
A balanced chemical equation is based on the law of?
A
Periodicity
B
Constant composition
C
Multiple proportion
D
Conservation of mass
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The law of conservation of mass is important because it allows us to predict the amount of product formed in a chemical reaction, as well as the amount of consumed reactant.
Source: Myschool Past Questions Archive (Record #58846)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
Which of the following pairs of elements has the greatest difference in electronegativity?
A
Na and F
B
Na and CI
C
Na and Br
D
Na and I
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
- sodium has an electro negativity of 0.93
- Hence; sodium and flourine have the highest difference.
Fluorine
4.0
Chlorine
3.0
Bromine
2.8
Iodine
2.5
Source: Myschool Past Questions Archive (Record #58852)
Chemistry
WAEC / WASSCE 2020
Matter & Separation Techniques
A factor that is considered most important when siting a chemical industry is?
A
nearness to other industrial establishments
B
nearness to raw materials
C
favourable climate conditions
D
availability of storage facilities
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 #58856)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
The boiling point of pentane is higher than that of propane because?
A
carbon-carbon single bonds are stronger than carbon-hydrogen bonds.
B
Pentane has more covalent bonds to break
C
Pentane does not burn easily as
propane
D
The intermolecular forces in pentane are stronger than those of propane
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The boiling points of alkanes increase with increasing number of carbons. This is because the intermolecular attractive forces, although individually weak, become cumulatively more significant as the number of atoms and electrons in the molecule increases.
Source: Myschool Past Questions Archive (Record #58862)
Chemistry
WAEC / WASSCE 2020
Matter & Separation Techniques
Solution
Which of the following solids would not decompose on heating?
A
Ammonium chloride
B
Lead (i) trioxonitrate (V)
C
Potassium trioxocarbonate (IV)
D
Sodium hydrogen trioxocarbonate (IV)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
trioxoxcarbonates (iv) of Na & K are stable to heat
Source: Myschool Past Questions Archive (Record #58874)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
The following molecules have double covalent bonds between two atoms except?
A
oxygen
B
carbon (IV)oxide
C
ethene
D
water
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
In the case of water, hydrogen bonds form between neighboring hydrogen and oxygen atoms of adjacent water molecules. The attraction between individual water molecules creates a bond known as a hydrogen bond.
Source: Myschool Past Questions Archive (Record #58881)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
The type of isomerism exhibited by cis and trans isomers is?
A
positional
B
geometrical
C
functional
D
optical
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
- Cis–trans isomerism, also known as geometric isomerism or configurational isomerism arises when atoms or groups are arranged differently in space due to restricted rotation of a bond or bonds in a molecule.
Source: Myschool Past Questions Archive (Record #58884)
Chemistry
WAEC / WASSCE 2020
Stoichiometry & Mole Concept
An alkanol containing 60% carbon by mass would have a molecular formula [H=1.0. C-12.0, O= 16.0]
A
CH\(_3\)OH
B
C\(_2\)H\(_5\)OH
C
C\(_3\)H\(_7\)OH
D
C\(_4\)H\(_9\)OH
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 #58896)
Chemistry
WAEC / WASSCE 2020
Matter & Separation Techniques
Which of the following compounds would release hydrogen when reacted with sodium metal?
I. CH\(_3\)COOH
II. CH\(_3\)CH\(_2\)OH
III. CH\(_3\)COOCH\(_3\)
A
I only
B
I and II only
C
Il and IIl only
D
I and Ill 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 #58911)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
Which of the following substances is not a reducing agent?
A
C
B
CO
C
O\(_2\)
D
H\(_2\)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
- A reducing agent is oxidized, because it loses electrons in the redox reaction.
- Elemental oxygen is a strong oxidizing agent.
Source: Myschool Past Questions Archive (Record #58921)