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Chemistry
WAEC / WASSCE 2021
Matter & Separation Techniques
Diagram
Solution
Which of the following cell notations represent the diagram?
Attached Figure / Diagram
A
B\(^{2+}\)/B/ /A/A\(^{3+}\)
B
A\(^{3+}\) /A/ /B/B\(^{2+}\)
C
B/B\(^{2+}\)/ /A/\(^{3+}\)
D
A/A\(^{3+}\)/ /B\(^{2+}\)/B
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The shorthand notation is A/A\(^{3+}\)//B\(^{2+}\)/B.
Source: Myschool Past Questions Archive (Record #62085)
Chemistry
WAEC / WASSCE 2021
Electrochemistry and Redox
Which of the following half reaction equations represent the reaction at the cathode
A
A\(^{3+_{(aq)}}\)+3e\(^{-}\) \(\rightarrow\) A\(_{(s)}\)
B
B\(^{2+_{(aq)}}\)+2e\(^{-}\) \(\rightarrow\) B\(_{(s)}\)
C
A\(_{(s)}\) \(\rightarrow\) \(^{3+_{(aq)}}\)+3e\(^{-}\)
D
B\(_{(s)}\) \(\rightarrow\) B\(^{2+_{(aq)}}\) + 2e\(^{-}\)
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 #62088)
Chemistry
WAEC / WASSCE 2021
Matter & Separation Techniques
The reactivity of fluorine is high because of
A
its high electronegativity
B
the small size of the fluorine atom
C
the availability of d-orbitals
D
the strong F-F bond
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 #62089)
Chemistry
WAEC / WASSCE 2021
Acids, Bases, and Salts
How many coulombs of electricity would liberate 1.08g of Ag from a solution of silver salt?
[Ag = 108.0; 1F = 96500 C]
A
96500 C
B
9650 C
C
965 C
D
9.65 C
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 #62091)
Chemistry
WAEC / WASSCE 2021
Matter & Separation Techniques
Which of the following statements is correct about ionization energy? It
A
decreases across the periods
B
results in the formation of an anion
C
causes Metalic nuclei to disintegrate
D
decreases down the group
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 #62099)
Chemistry
WAEC / WASSCE 2021
Matter & Separation Techniques
Potassium trioxonitrate (V) can be obtained from its solution by----------
A
distillation
B
evapoartion
C
crystallization
D
filtration
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 #62100)
Chemistry
WAEC / WASSCE 2021
Stoichiometry & Mole Concept
An element, Q, contains 69% of\(^{63}\)Q and 31% of \(^{65}\)Q. What is the relative atomic mass of Q?
A
63.0
B
63.6
C
65.0
D
69.0
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 #62101)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
Solution
The following ions have the same electron configuration except
\(_{8}\)O, \(_{12}\)Mg, \(_{13}\)AI, \(_{17}\)CI
A
CI\(^{-}\)
B
O\(^{2-}\)
C
Mg\(^{2+}\)
D
AI\(^{3+}\)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Electron Count Verification
To determine which ion does not share the same electron configuration, we calculate the number of electrons for each given ion using the formula:
Number of Electrons = Atomic Number - Charge
Option A: Cl\(^-\)
The atomic number of Chlorine (Cl) is 17.
A -1 charge means it has gained 1 electron.
Total electrons = 17 - (-1) = 18 electrons
(Configuration: 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^6\), matching Argon).
Total electrons = \(17 - (-1) = \mathbf{18\text{ electrons}}\) (Configuration: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\), matching Argon). [1]
Source: Myschool Past Questions Archive (Record #62104)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
The region around the nucleus where electrons can be located is called?
A
a spectra
B
an orbital
C
a quanta
D
a field
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 #62105)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
The isotopes of neon are represented by the symbols \(^{20}\)\(_{x}\) Ne, \(^{21}\) \(_{y}\) Ne, and \(^{22}\) \(_{z}\) Ne. The relationship between x, y, and z is?
A
x > y > z
B
x < y < z
C
x = y= z
D
x < z < y
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 #62118)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
Solution
Which of the following statements about elements in Group VII is correct?
A
B\(r_2\) will oxidize CI\(^{-}\)
B
\(F_2\) has the least tendency to be reduced
C
C\(l_2\) will oxidize I\(^{-}\)
D
\(l_2\) is a stronger oxidizing agent than \(F_2\)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Cl\(_2\) can oxidize I\(^-\). Chlorine (Cl\(_2\)) is a stronger oxidizing agent than iodine (I\(_2\)), meaning it can take electrons from other substances more readily. In a reaction between Cl\(_2\) and I-, the Cl\(_2\) will gain electrons from I\(_2\) oxidizing I- to I\(^-\).and reducing Cl\(_2\)to Cl\(^-\).
Source: Myschool Past Questions Archive (Record #62127)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
Electrovalent compounds normally ------------
A
have low boiling points
B
have mobile electrons
C
conduct electricity in the solid state
D
dissolve in polar solvent
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 #62129)
Chemistry
WAEC / WASSCE 2021
Atomic Structure and Periodic Table
Protons and electrons are called fundamental particles because they----------
A
are indivisible
B
have different charges
C
are the lightest particles
D
are found in all matter
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 #62106)
Chemistry
WAEC / WASSCE 2021
Kinetics, Energetics and Equilibrium
The activation energy of the reaction is
A
\(E_A\)
B
\(E_B\)
C
\(E_C\)
D
\(E_D\)
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 #62107)
Chemistry
WAEC / WASSCE 2021
Kinetics, Energetics and Equilibrium
Diagram
Solution
The enthalpy change of the reaction is------------
Attached Figure / Diagram
A
\(E_A\)
B
\(E_B\)
C
\(E_C\)
D
\(E_D\)
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Enthalpy change, \DeltaH = \DeltaH\(_{product}\) - \DeltaH\(_{reactant}\)
From the diagram E\(_D\) represents the enthalpy change, \DeltaH.
Source: Myschool Past Questions Archive (Record #62108)