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Chemistry
WAEC / WASSCE 2017
Kinetics, Energetics and Equilibrium
Solution
The property of a chemical reaction that is affected by the presence of a catalyst is
A
activation energy
B
free energy
C
equilibrium position
D
enthalpy change
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The activation energy is the amount of energy that is required to form products in a reaction. The presence of a catalyst helps to speed up the reaction such that the energy needed for the reaction is reduced.
Source: Myschool Past Questions Archive (Record #49315)
Chemistry
WAEC / WASSCE 2017
Acids, Bases, and Salts
Solution
Soluble salts can be prepared by the following methods except
A
neutralization
B
reaction of an acid with trioxocarbonate(IV) salt
C
double decomposition
D
reaction of an acid with electropositive metals
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Soluble salts cannot be produced by double decomposition( precipitation of an insoluble salt)
Source: Myschool Past Questions Archive (Record #49318)
Chemistry
WAEC / WASSCE 2017
Kinetics, Energetics and Equilibrium
Solution
Chemical reactions occurs when the colliding reactants have energy that is
A
less than the activation energy
B
greater than the activation energy
C
greater than the energy of the product
D
less than the energy of effective collision
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The energy of the reactants must be more than the activation energy in order for product to be formed.
Source: Myschool Past Questions Archive (Record #49320)
Chemistry
WAEC / WASSCE 2017
Electrochemistry and Redox
Solution
The common feature of reactions at the anode is that
A
electrons are consumed
B
ions are reduced
C
oxidation is involved
D
the electrode dissolves
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
In both the electrochemical cell and the electrolytic cell, at the anode, oxidation is involved.
Source: Myschool Past Questions Archive (Record #49323)
Chemistry
WAEC / WASSCE 2017
Electrochemistry and Redox
Solution
Consider the following reaction equation: \(2NO_{(g)} + O_{{2}{(g)}} \to 2NO_{{2}{(g)}}\). What is the change in the oxidation number of nitrogen?
A
+2 to 0
B
+2 to -2
C
+2 to +4
D
+4 to +2
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
In NO, the oxidation number for nitrogen is N - 2 = 0
⇒ N = +2
In \(NO_{2}\), we have N - (2x2) =0
N - 4 =0
N =+4
Source: Myschool Past Questions Archive (Record #49324)
Chemistry
WAEC / WASSCE 2017
Matter & Separation Techniques
Solution
Which of the following factors characterize members of the same homologous series?
A
The chemical property change gradually throughout the series
B
physical properties of members are similar
C
They have the same molecular formular
D
Successive members undergo changes in molecular formula by \(CH_{2}\)
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The difference between every successive member of the same homologous series is always \(CH_{2}\) eg methane is \(CH_{4}\) and ethane is \(C_{2}H_{6}\), difference being \(CH_{2}\).
Source: Myschool Past Questions Archive (Record #49326)
Chemistry
WAEC / WASSCE 2017
Stoichiometry & Mole Concept
Solution
Calculate the mass of copper deposited if a current of 0.45A flows through \(CuSO_{4}\) solution for 1hour 15mins. [Cu=64.0, S= 32.0, O =16.0, 1F= 96500C]
A
6.40g
B
0.67g
C
0.64g
D
0.45g
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
\(Cu^{2+} + 2e^{-} \to Cu_{(s)}\)
\( 2 \times 96500C = 193000C deposits 64g of Cu\)
\(M \propto It\)
\(Q = It = 0.45A \times 1hr15mins\)
= \( 0.45 \times 75 \times 60\) [converting the time to seconds]
Quantity of electricity passed = 2025C
\(193000C \to 64g Cu\)
\(1C \to \frac{64}{193000}\)
\(2025C \to \frac{64}{193000} \times 2025\)
\(= 0.6715g \approxeq 0.67g\)
Source: Myschool Past Questions Archive (Record #49330)
Chemistry
WAEC / WASSCE 2017
Acids, Bases, and Salts
Solution
Classification of alkanols is based on the
A
number of carbon atoms present in the compound
B
molecular mass of the compound
C
molecular formula of the compound
D
number of alkyl groups bonded to the carbon having the hydroxyl group
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Alkanols can be classified as primary, secondary or tertiary, according to the number of alkyl groups attached to the carbon which bears the -OH group.
Source: Myschool Past Questions Archive (Record #49331)
Chemistry
WAEC / WASSCE 2017
Acids, Bases, and Salts
Solution
The name of the compound \(C_{4}H_{9}COOC_{3}H_{7}\) is
A
propyl pentanoate
B
pentyl propanoate
C
butyl propanoate
D
propyl butanoate
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The alkyl group is attached to the parent chain being a carboxylic acid. The name of the compound is gotten by writing the name of the attached alkyl group first and then the parent carboxylic acid is written but you change the -oic acid to -oate.
The alkyl group in this case is \(C_{3}H_{7}\)
The parent carboxylic acid is \(C_{4}H_{9}COOH\) which is pentanoic acid.
Hence, the name is propyl pentanoate.
Source: Myschool Past Questions Archive (Record #49334)
Chemistry
WAEC / WASSCE 2017
Matter & Separation Techniques
Which of the following pairs of gases are pollutants from car exhaust?
A
Nitrogen(II) oxide and Carbon(IV) oxide
B
Carbon(IV) oxide and Nitrogen
C
Carbon(II) oxide and Sulphur(IV) oxide
D
Carbon(II) oxide and oxygen
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 #49335)
Chemistry
WAEC / WASSCE 2017
Matter & Separation Techniques
Solution
Fats and oils can be obtained from any of the following sources except
A
paraffin oil
B
animals
C
groundnuts
D
palm kernel
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Paraffin oil is gotten from petroleum distillation and can't be a source of fats and oil.
Source: Myschool Past Questions Archive (Record #49336)
Chemistry
WAEC / WASSCE 2017
Matter & Separation Techniques
Solution
The condensation of two units of glucose will produce a dissacharide with the formula \(C_{12}H_{22}O_{11}\) which is
A
sucrose
B
maltose
C
galactose
D
mannose
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
A maltose is a dissacharide formed from two units of glucose.
Source: Myschool Past Questions Archive (Record #49337)
Chemistry
WAEC / WASSCE 2017
Matter & Separation Techniques
Solution
The IUPAC name for the compound \(ClCH_{2}CH_{2}OH\) is
A
1- chloropropanol
B
2-chloropropanol
C
1-chloroethanol
D
2-chloroethanol
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The parent chain for the compound is \(C_{2}H_{5}OH\) in which one of the hydrogen atoms is replaced by the Cl atom. Giving the chlorine the highest number while naming, we have 2- chloroethanol.
Source: Myschool Past Questions Archive (Record #49338)
Chemistry
WAEC / WASSCE 2017
Acids, Bases, and Salts
Solution
The real harmful effect of the release of chlorofluorocarbons into the atmosphere is that it eventually causes
A
excessive ultraviolet light from the sun to reach the earth surface
B
excessive release of infrared light from the sun to the earth surface
C
corrosive effect of the chemicals on humans and animals
D
acidic effect of chemicals on humans
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Chlorofluorocarbons are harmful to environment and living beings because it increases greenhouse gases in the environment which results in forming holes in the ozone layer.. And if this happens it will cause to an increase in the ultraviolet rays exposer, and which will make the earth's surface much hotter than usual.
Source: Myschool Past Questions Archive (Record #49341)
Chemistry
WAEC / WASSCE 2017
Stoichiometry & Mole Concept
Diagram
Solution
A primary alkanol has a molecular mass of 60. What is the structural formula of the compound? [C= 12.0, H= 1.0, O= 16.0)
Attached Figure / Diagram
A
A
B
B
C
C
D
D
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Alkanols have the formula \(C_{n}H_{2n+1}OH\).
⇒ \( 12n + (1\times (2n+1)) + 16.0 + 1.0 = 60\)
= (14n +18 = 60\)
\(n = \frac{60-18}{14} = \frac{42}{14} = 3\)
Hence, the alkanol is gotten by putting n=3,
=\(C_{3}H_{7}OH\)
Source: Myschool Past Questions Archive (Record #49342)