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Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm3 container at 20°C. The number of moles of gas in the sample is?
(R = 0.082 litre atm / deg mole)
A
1.00
B
2.00
C
3.00
D
4.00
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
PV = nRT
2.93 x 8.2 = 0.082 x 293 xn
∴ n = (2.93 x8.2) / (0.082 x 293)
n = 1
Source: Myschool Past Questions Archive (Record #12994)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Atoms of element X (with 2 electrons in the outer shell). combine with atoms of Y (with 7 electrons in the outer shell). Which of the following statements is FALSE? The compound formed?
A
has formula XY
B
is likely to be ionic
C
contains X2+ ions
D
contains Y- ions
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The compound formed by a mixture of X and Y will be \(XY_{2}\) not XY.
Source: Myschool Past Questions Archive (Record #12997)
Chemistry
UTME / JAMB 1991
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
The ions X- and Y+ are isoelectronic, each containing a total of 10 electrons.
How many protons are in the nuclei of the neutral atoms of X and Y respectively?
A
10 and 10
B
9 and 9
C
11 and 9
D
9 and 11
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
X- means one excess electron, hence 9 protons while Y +/- means one deficit electron hence 11 protons X and Y = 9 and 11
Source: Myschool Past Questions Archive (Record #12999)
Chemistry
UTME / JAMB 1991
Chemical Bonding & Intermolecular Forces
Which of the following represents the type of bonding present in ammonium chloride molecule?
A
Ionic only
B
Covalent only
C
Ionic and dative covalent
D
Dative covalent only
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 #13001)
Chemistry
UTME / JAMB 1991
Periodic Table & Periodicity
Which of the following is arranged in order of increasing electronegativity?
A
Chlorine, aluminium, magnesium, phosphorus, sodium
B
sodium, magnesium, aluminium, phosphorus, chlorine
C
Chlorine, phosphorus, phosphorous, aluminium, magnesium, sodium
D
Sodium, chlorine, phosphorus, magnesium, aluminium
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 #13002)
Chemistry
UTME / JAMB 1991
Air & Environmental Chemistry
Solution
A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of?
A
nitrogen
B
neon
C
argon
D
oxygen
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Alkaline pyrogallol absorbs 92
Source: Myschool Past Questions Archive (Record #13003)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following ions is a pollutant in drinking water even in trace amounts?
A
Ca2+
B
Hg2+
C
Mg2+
D
Fe2+
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 #13004)
Chemistry
UTME / JAMB 1991
Water, Solutions & Solubility
Solution
A sample of temporary hard water can be prepared in the laboratory by?
A
disolving calcium chloride in distilled water
B
saturating lime water with carbon (IV) oxide
C
saturating distilled water with calcium hydroxide
D
dissolving sodium hydrogen trioxocarbonate (IV) in some distilled water
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
A sample of temporary hard water can be prepared in the laboratory by saturating lime water with carbon (IV) oxide. This means passing CO\(_2\) in excess through lime water, Ca(OH)\(_2\) to first obtain CaCO\(_3\), which later changes to soluble calcium hydrogentrioxocarbonate (IV) by passing more CO\(_2\) which imparts temporary hardness to water.
Ca(OH)\(_2\) + CO\(_2\) → CaCO\(_3\) + H\(_2\)O
CaCO\(_3\) + CO\(_2\) + H\(_2\)O → Ca(HCO\(_3\))\(_2\)
Source: Myschool Past Questions Archive (Record #13031)
Chemistry
UTME / JAMB 1991
Water, Solutions & Solubility
A property of a colloidal dispersion which a solution does not have is?
A
the Tyndall effect
B
homogeneity
C
osmotic pressure
D
surface polarity
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 #13032)
Chemistry
UTME / JAMB 1991
Non-Metals & Their Compounds
Solution
50 cm\(^3\) of sulphur (IV) oxide, 800cm\(^3\) of ammonia, 450 cm\(^3\) of hydrogen chloride, 1.0 cm\(^3\)of Carbon(IV) oxide will respectively saturate 1.0 cm\(^3\) of water at 15^\circC. Which of the following is suitable for demonstrating the fountain experiment?
A
Sulphur (IV) oxide and hydrogen chloride
B
Carbon (IV) oxide and ammonia
C
Ammonia and hydrogen chloride
D
Carbon (IV) oxide and surphur (IV) oxide
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
The fountain experiment is a chemistry demonstration that shows the solubility of a gas in water. In the experiment, a soluble gas like ammonia or hydrogen chloride is placed in a flask and water is injected into the flask. The gas dissolves in the water, which lowers the pressure in the flask and causes water to be sucked in from another source. The fountain experiment demonstrates the highly soluble nature of hydrogen chloride and ammonia gas in water.
Source: Myschool Past Questions Archive (Record #13033)
Chemistry
UTME / JAMB 1991
Organic Chemistry I: Hydrocarbons & Crude Oil
How many structural isomers can be written for the alkyl bromide, C4H9Br?
A
3
B
4
C
6
D
8
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 #13034)
Chemistry
UTME / JAMB 1991
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
What volume of CO\(_2\) at s.t.p would be obtained by reacting 10cm\(^3\) of 0.1M solution of anhydrous sodium trioxocarbonate (IV) with excess acid?
(G.M.V at s.t.p = 22.4 dm\(^3\))
A
2.240 cm 3
B
22.40 cm 3
C
224.0 cm 3
D
2240 cm 3
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Na\(_2\)CO\(_3\) + 2HCl → 2NaCI + H\(_2\)O + CO\(_2\)
1000 cm\(^3\) IM Na\(_2\)CO\(_3\) contains 22400 cm\(^3\)
10 cm\(^3\) IM Na\(_2\)CO\(_3\) will contain (10) / (100) x 224
=224 cm\(^3\)
10 cm\(^3\) 0.1M Na\(_2\)CO\(_3\) will contain (0.1 x 224) / (1) = 22.4 cm\(^3\)
METHOD 2:
Na\(_2\)CO\(_3\) + 2HCl → 2NaCI + H\(_2\)O + CO\(_2\)
1 : 2 2 : 1 : 1
This implies 1 mole of Na\(_2\)CO\(_3\) produces 1 mole of CO\(_2\)
But n = \(\frac{CV}{1000}\)
Given: C = 0.1M, V = 10 cm\(^3\), n = ?
n = \(\frac{0.1 X 10}{1000}\) = 0.001 mole of Na\(_2\)CO\(_3\) will also produce 0.001 mole of CO\(_2\) following the stoichiometry in the balanced chemical equation above (1:1)
But we need to determine the volume of CO\(_2\) not the number of moles (amount), and since CO\(_2\) is a gas, we'll use the formula:
n = \(\frac{volume}{molar volume}\) = \(\frac{V}{G.M.V}\)
0.001 = \(\frac{V}{22.4}\)
V = 0.001 X 22.4 = 0.0224 dm\(^3\)
Since the all options were given in cm\(^3\), we'll convert to cm\(^3\) by multiplying by 1000 = 0.0224 x 1000 = 22.4 cm\(^3\)
Source: Myschool Past Questions Archive (Record #13050)
Chemistry
UTME / JAMB 1991
Electrolysis & Electrochemical Cells
Solution
If a current of 1.5 A is passed for 4.00 hours through a molten tin salt and 13.3g of tin is deposited, what is the oxidation state of the metal in the salt?
(Sn = 118.7, F = 96500 C mol-1)
A
1
B
2
C
3
D
4
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Q = It = 1.5 x 4 x 60 x 60
13.3 g = 216000 C
118.7 g = (216000 x118.7) / (13.3) = 1927759.4 C
06500 C - 1 mole
1927759.4 C = (1927759.4) / (96500) = 1.998 = 2
Source: Myschool Past Questions Archive (Record #13054)
Chemistry
UTME / JAMB 1991
Acids, Bases, pH & Salts
Which of the following equimolar solutions, Na2CO3 Na2 SO
4CI FeCI3 CH3COONa,
have pH greater than 7?
A
FeCI 3 and NH 4CI
B
Na2CO3, CH3COONa and Na,Na2SO4
C
Na2CO3 and CH3COONa
D
FeCI3, CH3COONa and NH4CI
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 #13058)
Chemistry
UTME / JAMB 1991
Oxidation, Reduction & Redox Reactions
Solution
MnO-4 + 8H+ + ne → Mn++ + 4H2O. Which is the value of n in the reaction above?
A
2
B
3
C
4
D
5
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
MnO-4 + 8H+ + ne- → Mn++ + 4H2O
Since Mn has 7 electrons on one side and 2 electrons on the other side. The value of ne- is 5.
Source: Myschool Past Questions Archive (Record #13060)