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Chemistry
UTME / JAMB 1993
Oxidation, Reduction & Redox Reactions
Solution
A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?
A
sulphur (ii) oxide
B
hydrogen sulphide
C
sulphide (lV) oxide
D
hydrogen chloride
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Sulphur dioxide (SO₂) gas will turn an orange solution of acidified potassium dichromate (K₂Cr₂O₇) clear green. This colour change occurs because sulphur dioxide is a reducing agent, and it reduces the dichromate ion (Cr₂O₇²⁻) from its orange form to the green chromium(III) form (Cr³⁺).
Source: Myschool Past Questions Archive (Record #13682)
Chemistry
UTME / JAMB 1993
Kinetic Theory of Matter & Gas Laws
Diagram
Which of the curves above represents the behaviour of 1 mole of an ideal gas?
Attached Figure / Diagram
A
l
B
ll
C
lll
D
lV
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 #31462)
Chemistry
UTME / JAMB 1993
Water, Solutions & Solubility
Diagram
Solution
For which salt in the graph above does the solubility increase most rapidly with rise in temperature?
Attached Figure / Diagram
A
CaSO4
B
KNO3
C
NaCl
D
KCl
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
For many solids that are dissolved in water or any liquid, the solubility increases with a temperature rise. With an increase in kinetic energy, the solvent molecules effectively break apart the solute molecules that are held together by strong intermolecular attractions, and thereby solubility is increased.
Source: Myschool Past Questions Archive (Record #31463)
Chemistry
UTME / JAMB 1993
Oxidation, Reduction & Redox Reactions
Diagram
Solution
Half-cell reaction. From the data above , it can be deduced that the most powerful reducing agent of the four metals is
Attached Figure / Diagram
A
Cu
B
Fe
C
Ba
D
Zn
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
elements with lower electrode potentials are most likely to be reduced and act as a reducing agent. Lower electrode potential indicates a greater tendency to accept electrons.
Source: Myschool Past Questions Archive (Record #31465)
Chemistry
UTME / JAMB 1993
Chemical Energetics & Thermochemistry
Diagram
In the diagram above, curve X represents the energy profile for a homogeneous gaseous reaction. Which of the following conditions would produce curve Y for the same reaction?
Attached Figure / Diagram
A
Increase in temperature
B
Increase in the concentration of a reactant
C
Addition of a catalyst
D
Increase in pressure
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 #31466)
Chemistry
UTME / JAMB 1993
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Diagram
Solution
The two functional groups in the above compound are
Attached Figure / Diagram
A
alcohol and amine
B
acid and amine
C
aldehyde and acid
D
ketone and amine
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The two functional groups in the above compound are alkanoic acid (-COOH) and amine (-NH\(_2\).
Source: Myschool Past Questions Archive (Record #31468)
Chemistry
UTME / JAMB 1993
Stoichiometry, Mole Concept & Volumetric Analysis
Diagram
The IUPAC nomenclature for the compound above is
Attached Figure / Diagram
A
dimethlhexane
B
3,5 dimethylhexane
C
1.1 dmethyl, 3 methylpentane
D
2.4 dimethylhexane
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 #31469)
Chemistry
UTME / JAMB 1993
Organic Chemistry I: Hydrocarbons & Crude Oil
Diagram
The function of the copper (ll)tetraoxosulphate (IV) in dilute H2SO4 in the figure above is to
Attached Figure / Diagram
A
dry the gas
B
absorb phosphine impurity
C
absorb ethene impurity
D
from an acetylide with ethyne
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 #31472)
Chemistry
UTME / JAMB 1993
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
At 25oC and 1atm, a gas occupies a volume of 1.50dm3. What volume will it occupy at 100oC and 1atm?
A
1.88 dm3
B
6.00 dm3
C
18.80 dm3
D
18.80 dm3
E
60.00dm3
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
\(\frac{v_1}{T_1} = \frac{V_2}{T_2}\)
V2 = \(\frac{V_1 \times T_2}{T_1}\)
= \(\frac{1.50 \times 373}{298}\)
= 1.88 dm3
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 1993
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
A solution containing 0.095 mol. dm\(^{-3}\) of trioxonitrate (V) acid. Solution B contains 13.50g of X\(_2\)CO\(_3\).10H\(_2\)O per dm\(^3\)
(a) Put A in the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used.
(b) From your results and the information provided, calculate the;
(i) Concentration of B in mol. dm\(^3\)
(ii) molar mass of X\(_2\)CO\(_3\).10H\(_2\)O
(iii) percentage by mass of X in X\(_2\)CO\(_3\).10H\(_3\)O. The equation for the reaction is X\(_2\)CO\(_3\) + 2HNO\(_3{(aq)}\) \(\to\) 2XNO\(_{3(aq)}\) + CO\(_{2(g)}\) + 11H\(_2\)O\(_{(l)}\) [H = 1, C = 12, O = 16]
(c) Give the reason for the following:
(i) using just a small quantity of the indicator during acid-base titrations.
(ii) obtaining at least two sets of readings for titration experiment.
A
lead and tin
B
iron and carbon
C
copper and tin
D
aluminium and copper
E
lead and antimony
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Volume of pipette = 25cm\(^3\)
Indicator - Methyl orange
Burette Readings
Rough
1st
2nd
3rd
Final Burette Readings (cm\^3\))
25.20
29.90
27.00
25.00
Initial Burette Reading (cm\(^3\))
0.00
5.05
2.20
0.10
Volume of acid used (cm\(^3\))
25.20
24.85
24.80
24.90
(a) Average volume of A used = \(\frac{24.85 + 24.80 + 24.90}{3}\) = 24.85
The equation for the reaction \(\to\) X\(_2\)CO\(_3\).10H\(_2\)O\(_{(aq)}\) + 2HNO\(_{3(aq)}\) \(\to\) 2XNO\(_{3(aq)}\) + CO\(_{2(g)}\) + 11H\(_2\)O\(_{(l)}\)
(b)(i) Mole ratio of Acid to Base is 2:1
\(\frac{C_AV_A}{C_BV_B}\) = \(\frac{2}{1}\)
\(\frac{0.095 \times 24.85}{C_B \times 25}\) = \(\frac{2}{1}\)
C\(_B\) = \(\frac{0.095 \times 24.85}{2 \times 25} = 0.0472\) mol. dm\(^{-3}\)
(ii) Molar mass of X\(_2\)CO\(_3\).10H\(_2\)O = \(\frac{\text{mass concentration}}{\text{molar concentration}}\) = \(\frac{13.50}{0.0472}\) = 286 mol\(^{-1}\)
(iii) Relative molar mass of X\(_2\)CO\(_3\).H\(_2\)O = 286
2X + 12 + (16 x 3) + 10((2 x 1) + 16) = 286
2X + 240 = 286
2X = 46
Percentage by mass of X is X\(_2\)CO\(_3\).10H\(_2\)O = \(\frac{46}{280}\) x 100% = 16.08%
(c)(i) In order to obtain sharp and clear colour change at end point
(ii) For consistency or accuracy of titre values
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 1993
Nature of Matter & Separation Techniques
Which of the following separation is routinely applied in the petroleum industry
A
Filtration
B
Chromatography
C
Evaporation
D
Fractional crystallization
E
Fractional distillation
medium Difficulty
Verified Correct Answer: Option E
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #36253)
Chemistry
WAEC / WASSCE 1993
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Starch undergoes complete hydrolysis to produce
A
maltose
B
lactose
C
fructose
D
glucose
E
sucrose
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 #36254)
Chemistry
WAEC / WASSCE 1993
Non-Metals & Their Compounds
Solution
Which of the following solids has a network structure?
A
Diamond
B
lodine
C
Sulphur
D
Graphite
E
lron
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
A solid with a network structure is diamond. Diamond is a covalent network solid where each carbon atom is covalently bonded to four other carbon atoms, creating a continuous three-dimensional network.
Source: Myschool Past Questions Archive (Record #36255)
Chemistry
WAEC / WASSCE 1993
Stoichiometry, Mole Concept & Volumetric Analysis
Trioxosulphate (lV) acid is not stored for a long period because it
A
is a weak dibasic acid
B
has bleaching properties
C
is unstable and eaily decomposed
D
smells strongly of sulphur (lV) oxide
E
can act as a germicide
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 #36256)
Chemistry
WAEC / WASSCE 1993
Organic Chemistry I: Hydrocarbons & Crude Oil
Alkanes are used mainly
A
in the production of plastics
B
as domestic and industrial fuels
C
in the textile industry
D
in the hydrogenation of oils
E
as fine chemicals
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 #36257)