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Chemistry
WAEC / WASSCE 2019
Acids, Bases, and Salts
The process by which alkanoic acid reacts reversibly with alkanols is known as?
A
saponification
B
esterification
C
carboxylation
D
halogenation
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 #58176)
Chemistry
WAEC / WASSCE 2019
Kinetics, Energetics and Equilibrium
Solution
consider the reaction represented by the following equation: 2SO\(_2\) + O\(_2\) ⇌ 2SO\(_3\)
A decrease in the pressure of the reaction would
A
decrease in the concentration of SO\(_2\)
B
have no effect on the reaction
C
shift the equilibrium position to the left
D
shift the equilibrium position to the right
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
decrease in pressure favors the side with higher volume thus the equilibrium position will shift to the left
Source: Myschool Past Questions Archive (Record #58181)
Chemistry
WAEC / WASSCE 2019
Matter & Separation Techniques
Solution
In a mixture of gases which do not react chemically together, the pressure of the individual gas is?
A
atmospheric pressure
B
vapor pressure
C
total pressure
D
partial pressure
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The pressure exerted by an individual gas in a mixture is known as its partial pressure
Source: Myschool Past Questions Archive (Record #58186)
Chemistry
WAEC / WASSCE 2019
Acids, Bases, and Salts
Solution
Biotechnology is applied in the?
A
treatment of sewage
B
treatment of water
C
purification of chemicals
D
purification of metals
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
There are several wastewater treatment methods based on biotechnology that are used worldwide. It includes Activated Sludge, Oxidation Ponds, Tricking Filters, Bio-filters and Anaerobic treatment. All the methods are part of the biological wastewater treatment and use microbes to treat organic waste in sewage.
Source: Myschool Past Questions Archive (Record #58190)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
which of the following organic compounds has the lowest boiling point?
A
C\(_6\)H\(_14\)
B
C\(_5\)H\(_12\)
C
C\(_4\)H\(_10\)
D
( CH\(_3\) )\(_3\)
medium Difficulty
Verified Correct Answer: Option D
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.
- However; branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content. This occurs because of the greater van der Waals forces that exist between molecules of the unbranched alkanes
Source: Myschool Past Questions Archive (Record #58427)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
Consider the following reaction represented by the following equation:
C\(_2\)H\(_2\) \(^{H_2}_{→}\) X \(^{H_2}_{→}\) Y. X and Y respectively are?
A
ethane and ethene
B
ethene and ethane
C
ethyne and ethene
D
ethane and ethyne
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The reaction between ethyne (C₂H₂) and hydrogen (H₂) is a hydrogenation reaction, specifically an addition reaction where hydrogen atoms add across the triple bond of ethyne, breaking the triple bond to form a C=C first, i.e ethene. Then on further reaction, the C=C reacts with H\(_2\), breaking the C=C to form a C-C bond. i.e ethane (C₂H₆).
C\(_2\)H\(_2\) \(^{H_2}_{→}\) X \(^{H_2}_{→}\) Y.
C\(_2\)H\(_2\) \(^{H_2}_{→}\) C\(_2\)H\(_4\) \(^{H_2}_{→}\) C\(_2\)H\(_6\)
Source: Myschool Past Questions Archive (Record #58435)
Chemistry
WAEC / WASSCE 2019
Acids, Bases, and Salts
Solution
Which of the following substances can be classified as heavy chemicals?
A
CaOCl\(_2\)
B
H\(_2\)SO\(_4\)
C
AgNO\(_3\)
D
CaO
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
- heavy chemicals are produced and handled in large lots and are often in a crude state.
- Some examples of bulk chemicals are ammonia, sulfuric acid, and sodium hydroxide
- Fine chemicals are single, pure and complex chemicals that are only produced in small amounts
Source: Myschool Past Questions Archive (Record #58441)
Chemistry
WAEC / WASSCE 2019
Matter & Separation Techniques
Solution
in Boyle's law?
A
T is constant, P varies directly with V
B
P is constant, V varies inversely with T
C
V is constant, P varies directly with T
D
T is constant, V varies inversely with P
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Boyle's law states that the pressure (p) of a given quantity of gas varies inversely with its volume (v) at constant temperature; i.e., in equation form, pv = k, a constant. ...
Source: Myschool Past Questions Archive (Record #58486)
Chemistry
WAEC / WASSCE 2019
Stoichiometry & Mole Concept
Solution
Which of the following apparatus is NOT used in volumetric analysis?
A
Pipette
B
Burette
C
Desiccator
D
conical flask
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
- The most common apparatus used in volumetric determinations are the pipette,buret, measuring cylinder, volumetric and conical (titration) flask.
- A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity.
Source: Myschool Past Questions Archive (Record #58491)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
One of the deductions from Rutherford's alpha particle scattering experiment is that?
A
electrons are negatively charged
B
electrons have a negligible mass
C
nuclei of atoms are positively charged
D
protons are positively charged
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The model of an atom put forward by Ernest Rutherford in 1911 on the basis of experiments on the scattering of alpha particles. The model consisted of a very dense positively charged nucleus, with electrons orbiting round the nucleus.
Source: Myschool Past Questions Archive (Record #58501)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
The atoms of \(^{64}_{29}\)Cu and \(^{65}_{30}\)Zn have the same number of?
A
nucleon
B
electrons
C
neutrons
D
protons
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The atomic mass is written as superscript = proton number + neutron number
- Atomic mass of Cu is 64 = 29 + 35
- Atomic mass of Zn is 65 = 30 + 35
Proton number is written as subscript
Source: Myschool Past Questions Archive (Record #58503)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
The number of electrons in the 3d orbital of \(_24\)Cr is
A
2
B
3
C
4
D
5
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Its electronic configuration in ground state is 1s2 2s2 2p6 3s2 3p6 4s1 3d5.
Source: Myschool Past Questions Archive (Record #58507)
Chemistry
WAEC / WASSCE 2019
Matter & Separation Techniques
Solution
The method used to collect gas in the laboratory depends on its?
I. boiling point II. density III. smell IV. solubility in water
A
i and ii only
B
ii and iv only
C
iii and iv
D
i, ii, iii and iv
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The method of collecting a gas produced by a chemical reaction will depend on its solubility and its density.
Source: Myschool Past Questions Archive (Record #58509)
Chemistry
WAEC / WASSCE 2019
Matter & Separation Techniques
Solution
Which of the following methods is NOT used for the separation of mixtures?
A
Chromatography
B
Crystallization
C
Distillation
D
Electrolysis
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Uses of electrolysis:
Electrolysis is used in the extraction of metals from their ores.
It is used for refining certain metals such as copper and zinc.
Electrolysis is used for the manufacture of chlorine.
Electrolysis is used for electroplating many things we use every day.
Source: Myschool Past Questions Archive (Record #58512)
Chemistry
WAEC / WASSCE 2019
Atomic Structure and Periodic Table
Solution
The group to which elements belong in the periodic table is determined by the number?
A
electrons
B
core electrons
C
valence shells
D
valence electrons
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
This periodic table shows the valences of element groups.
Source: Myschool Past Questions Archive (Record #58514)