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Chemistry
UTME / JAMB 1999
Acids, Bases, pH & Salts
Solution
The solution with the lowest pH value is
A
5 ml of (m/10) HCl
B
10 ml of (m/10) HCl
C
15 ml of (m/5) HCl
D
20 ml of (m/8) HCl
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
pH = - Log[\(H^+\)]. All we need is the concentration of the acid, and not the volume.
Option A : 5ml of \(\frac{M}{10}\)HCl; [\(H^+\)] = \(\frac{M}{10}\)= \(\frac{1}{10}\times M\) = 0.1M. pH = - Log(0.1)= 1
Option B : 10ml of \(\frac{M}{10}\)HCl;[\(H^+\)] = \(\frac{M}{10}\)= \(\frac{1}{10}\times M\) = 0.1M. pH = - Log(0.1)= 1
Option C : 15ml of \(\frac{M}{5}\)HCl; [\(H^+\)] = \(\frac{M}{5}\)= \(\frac{1}{5}\times M\) = 0.2M. pH = - Log(0.2)= 0.699
Option D : 20ml of \(\frac{M}{8}\)HCl; [\(H^+\)] = \(\frac{M}{8}\)= \(\frac{1}{8}\times M\) = 0.125M. pH = - Log(0.125)= 0.903
Among the options, option C tends to have the least pH value of 0.699
Source: Myschool Past Questions Archive (Record #1389)
Chemistry
UTME / JAMB 1999
Water, Solutions & Solubility
Solution
The solubility product of Cu(IO3)2 is 1.08 * 10-7. Assuming that neither ions react appreciable with water to form H+ and OH-, what is the solubility of this salt?
A
2.7 * 10-8 mol dm-3
B
9.0 * 10-8 mol dm-3
C
3.0 * 10-3 mol dm-3
D
9.0 * 10-3 mol dm-3
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
On dissociation, Cu(IO\(_3\))\(_2\) ⇌ Cu\(^{2+}\)(aq) + 2IO\(_3\)\(^-\)(aq).
Solubility product constant = Ksp
The formula is : Ksp = [Cu\(^{2+}\)] [IO\(_3\)\(^-\)]\(^2\)
Let the concentrations of Cu\(^{2+}\) and IO\(_3\)\(^-\) be expressed as d.
[Cu\(^{2+}\)] = d ; [ IO\(_3\)\(^-\)] = 2d (because 2IO\(_3\)\(^-\) )
Substituting these expressions into the Ksp
Ksp = [Cu\(^{2+}\)] [IO\(_3\)\(^-\)]\(^2\)
Ksp = (d) x (2d)\(^2\)
Ksp = d.4d\(^2\)
Ksp = 4d\(^3\)
Recall that Ksp = 1.08 x 10\(^{-7}\)
4d\(^3\) = 1.08 x 10\(^{-7}\)
Divide both sides by 4
d\(^3\) = \(\frac{1.08 x 10^{-7}}{4}\)
d\(^3\) = 0.000000027
d = ∛0.000 000 027
d = 0.003
d = 3 x 10\(^{-3}\) moldm\(^{-3}\)
Source: Myschool Past Questions Archive (Record #1391)
Chemistry
UTME / JAMB 1999
Chemical Energetics & Thermochemistry
The entropy and enthalpy of a system are a measure of
A
degree of disorderlinesss and heat content respectively
B
heat content and degree of disorderliness respectively
C
heat content of a system only
D
degree of disorderliness only
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 #1393)
Chemistry
UTME / JAMB 1999
Stoichiometry, Mole Concept & Volumetric Analysis
2SO2(g) + O2(g) ↔ 2SO3(g). In the chemical reaction above, the substance that will increase the rate of production of sulphur (VI) oxide is
A
manganese (IV) oxide
B
finely divided iron
C
vanadium (V) oxide
D
nickel
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 #1396)
Chemistry
UTME / JAMB 1999
Reaction Rates & Chemical Equilibrium
Solution
N\(_2\)O\(_4\)(g) ↔ 2NO\(_2\)(g). Increase in total pressure of the equilibrium reaction above will
A
produce more of NO2(g) in the mixture
B
convert all of N2O4(g) to NO2(g)
C
have no effect on the concentrations of NO2(g)and N2O4(g)
D
produce more of N2O4(g) in the mixture
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
An increase in pressure on a system at equilibrium, according to Le Chatelier's principle, shifts the equilibrium towards the side with fewer moles of gas to relieve the stress of increased pressure.
In the above reaction, the side with the lesser number of moles of gaseous species is the reactant,N\(_2\)O\(_4\) with 1 mole as against the product side with 2 moles. Hence, an increase in total pressure will favour the side with the lesser number moles. This implies more N\(_2\)O\(_4\) will be produced.
Source: Myschool Past Questions Archive (Record #1399)
English Language
WAEC / WASSCE 1999
Concord (Subject-Verb Agreement)
From the words lettered A to D, choose the word that best completes each of the following sentences.
My parents do not........late night parties
A
indulge
B
suffer
C
tolerate
D
create
medium Difficulty
Verified Correct Answer: Option C
Grammar & Contextual Explanation
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #24609)
English Language
WAEC / WASSCE 1999
Concord (Subject-Verb Agreement)
From the words lettered A to D, choose the word that best completes each of the following sentences.
I have known him only recently so I cannot ............ for his honesty
A
sign
B
stand
C
vouch
D
support
medium Difficulty
Verified Correct Answer: Option C
Grammar & Contextual Explanation
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #24610)
English Language
WAEC / WASSCE 1999
Concord (Subject-Verb Agreement)
From the words lettered A to D, choose the word that best completes each of the following sentences.
In some cultures, dead people are buried, but in others they are............
A
cremated
B
baked
C
fired
D
flamed
medium Difficulty
Verified Correct Answer: Option A
Grammar & Contextual Explanation
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #24611)
English Language
WAEC / WASSCE 1999
Concord (Subject-Verb Agreement)
From the words lettered A to D, choose the word that best completes each of the following sentences.
The lady is a .......beauty.
A
raging
B
ravaging
C
ravenous
D
ravishing
medium Difficulty
Verified Correct Answer: Option D
Grammar & Contextual Explanation
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #24612)
English Language
WAEC / WASSCE 1999
Concord (Subject-Verb Agreement)
From the words lettered A to D, choose the word that best completes each of the following sentences.
In some countries, it is an offence to describe a child born out of wedlock as .........
A
illegal
B
illegitimate
C
illicit
D
illiterate
medium Difficulty
Verified Correct Answer: Option B
Grammar & Contextual Explanation
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #24613)
Chemistry
UTME / JAMB 1999
Stoichiometry, Mole Concept & Volumetric Analysis
The gas that will form a white precipitate with acidified silver trioxonitrate (v) is
A
NH3
B
SO2
C
CO2
D
HCL
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 #1461)
Chemistry
UTME / JAMB 1999
Oxidation, Reduction & Redox Reactions
The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is
A
Na2SO4
B
Na2SO3
C
Na2S
D
Na2CO3
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 #1465)
Chemistry
UTME / JAMB 1999
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
A pair of compounds that can be used to generate a gas which has physiological effect on human beings is
A
sodium trioxonitrate (V) and calcium chloride
B
sodium dioxonitrate (III) and ammonium chloride
C
sodium trioxonitrate (V) and ammonium chloride
D
sodium dioxonitrate (III) and potassium chloride
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The reaction between NaNO\(_3\) and NH\(_4\)Cl gives NaCl and NH\(_4\)NO\(_3\).
Upon heating, NH\(_4\)NO\(_3\) yields 2 moles of H\(_2\)O and N\(_2\)O.
Source: Myschool Past Questions Archive (Record #1467)
Chemistry
UTME / JAMB 1999
Stoichiometry, Mole Concept & Volumetric Analysis
Hydrogen is used in oxy-hydrogen flames for melting metals because it
A
evolves a lot of heat when burnt
B
combines explosively with oxygen
C
is a very light gas
D
is a rocket fuel
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 #1469)
Chemistry
UTME / JAMB 1999
Electrolysis & Electrochemical Cells
Solution
What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?
[ F = 96 5000 C mol-1 ]
A
24 125 coulombs
B
48 250 coulombs
C
72 375 coulombs
D
96 500 coulombs
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
4 Faradays of electricity is required to liberate one mole of oxygen gas
∴ quantity of electricity required
= 0.125 * 4 * 96500 = 48250 coulombs
Source: Myschool Past Questions Archive (Record #1402)