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Chemistry
WAEC / WASSCE 2009
Atomic Structure and Periodic Table
An element Q forms a compound QCI5. In which group of the periodic table is Q?
A
l
B
lll
C
V
D
VII
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 #37332)
Chemistry
WAEC / WASSCE 2009
Atomic Structure and Periodic Table
Solution
Which of the statements about the behaviour of the atom is correct?
A
atomic size decreases down the group
B
atomic size increases across the period
C
anions are smaller than the parent atom
D
cations are smaller than the parent atom
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Cations (positively charged ions) are smaller than their parent atoms because the loss of electrons reduces electron-electron repulsion and increases the effective nuclear charge, pulling the remaining electrons closer to the nucleus.
Source: Myschool Past Questions Archive (Record #37338)
Chemistry
WAEC / WASSCE 2009
Atomic Structure and Periodic Table
Which of the following properties of covalent compounds is not correct? They
A
are non-electrolytes
B
are mostly gaseous and volatile liquids
C
have low melting point
D
have high boiling points
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 #37340)
Chemistry
WAEC / WASSCE 2009
Matter & Separation Techniques
Which of the following arrangements is in order of increasing ionization energy?
A
AI, Si, P, S
B
Si, AI,S,P
C
S,P,Si,AI
D
P, Si,S,AI
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 #37341)
Chemistry
WAEC / WASSCE 2009
Atomic Structure and Periodic Table
In bonded atoms, increase in electronegativity difference,
A
increases polarity
B
decreases polarity
C
has no effect on polarity
D
brings the polarity to zero
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 #37342)
Chemistry
WAEC / WASSCE 2009
Stoichiometry & Mole Concept
Which of the following molecules is not linear in shape?
A
CO2
B
O 2
C
NH3
D
HCI
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 #37343)
Chemistry
WAEC / WASSCE 2009
Stoichiometry & Mole Concept
The number of particles in one mole of a chemical compound is the
A
atomic number
B
avogadro's number
C
mass number
D
oxidation number
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 #37344)
Chemistry
WAEC / WASSCE 2009
Stoichiometry & Mole Concept
Solution
How many molecules are there in 14 g of nitrogen at s.t.p.? [N = 14, Avogadro's constant = 6.02 x 10\(^{23}\) mol-1]
A
6.02 x 1023
B
3.01 x 1023
C
8.43 x 1024
D
1.20 x 1024
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Given:
mass, m = 14g
Molar mass of N\(_2\) = 14 X 2 = 28g/mol
number of moles, n = ?
But n = \(\frac{m}{M}\) = \(\frac{14}{28}\)
n = 0.5 mole
Also, recall that Number of moles = \(\frac{Number of Molecules}{Avogadro number}\)
n = \(\frac{N}{L}\)
N = n x L
= 0.5 x 6.02 x 10\(^{23}\)
= 3.01 x 10\(^{23}\) molecules
Source: Myschool Past Questions Archive (Record #37348)
Chemistry
WAEC / WASSCE 2009
Stoichiometry & Mole Concept
Consider the reaction represented by the equation: 2NaHCO3 → Na2CO 3 + H 2O + CO 2. What is the mass of sodium trioxocarbonate (lV) produced by the complete decomposition of 33.6 g of sodium hydrogen trioxocarbonate (IV)? [NaHCO3 = 84, Na2CO3 = 106]
A
10.6 g
B
16.8 g
C
21.2 g
D
42.4 g
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 #37349)
Chemistry
WAEC / WASSCE 2009
Matter & Separation Techniques
What is the percentage by weight of calcium in Ca(OCI)2? [Ca = 40, Cl = 35.5, O = 16]
A
28.0%
B
31.6%
C
43.8%
D
44.5%
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 #37359)
Chemistry
WAEC / WASSCE 2009
Matter & Separation Techniques
Salts that contain water of crystallization are said to be
A
anhydrous
B
deliquescent
C
efflorescent
D
hydrated
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 #37371)
Chemistry
WAEC / WASSCE 2009
Acids, Bases, and Salts
Which of the following dilute acids does not react with metals to liberate hydrogen?
A
CH3COOH(aq)
B
HCI(aq)
C
H2SO4(aq)
D
HNO3(aq)
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 #37375)
Chemistry
WAEC / WASSCE 2009
Acids, Bases, and Salts
Which of the following compounds is not a double salt?
A
Zn(OH)NO3
B
KAI(SO4)2
C
KCr(SO4)2
D
(NH4)2Fe(SO4)2
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 #37379)
Chemistry
WAEC / WASSCE 2009
Matter & Separation Techniques
Which of the following hydroxides will readily dissolved in water?
A
Cu(OH)2
B
NaOH
C
Pb(OH)2
D
Zn(OH)2
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 #37380)
Chemistry
WAEC / WASSCE 2009
Acids, Bases, and Salts
Solution
Which of the following acids from normal salt only?
A
Tetraoxosulphate (IV) acid
B
Tetraoxophosphate (V) acid
C
Trioxonitrate (V) acid
D
Trioxosulphate (IV) acid
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Normal salts, also known as neutral salts, are formed through the complete neutralization of a strong acid and a strong base, where the ionizable hydrogen atoms of the acid are completely replaced by a metallic or ammonium ion.
Trioxonitrate(v) acid will only form one type of salt because it is a monobasic acid i.e. it contains only one replaceable hydrogen atom.
Source: Myschool Past Questions Archive (Record #37390)