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Chemistry
UTME / JAMB 1997
Kinetic Theory of Matter & Gas Laws
Solution
If 30cm\(^3\) of oxygen diffuses through porous plug in 7s, how long will it take 60 cm\(^3\) of chlorine to diffuse through the same plug?
A
12s
B
14s
C
21s
D
30s
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Given:
t\(_c\) = ? V\(_c\) = 60cm\(^3\) , M\(_c\) = 35.5 x 2 = 71
t\(_o\) = 7s; V\(_o\) = 30cm\(^3\) , M\(_o\) = 16 x 2 = 32
According to Graham's law of diffusion, R ∝ 1/\sqrtM
\(\frac{R_o}{R_c}\) = \(\sqrt{\frac{M_c}{M_o}}\)
Also, Rate of diffusion = \(\frac{Volume}{time}\)
\(\frac{R_o}{R_c}\) = \(\frac{V_o}{t_o}\) \div \(\frac{V_c}{t_c}\) = \(\frac{V_o}{t_o}\) X \(\frac{t_c}{V_c}\)
Therefore, \(\frac{V_o}{t_o}\) X \(\frac{t_c}{V_c}\) = \(\sqrt{\frac{M_c}{M_o}}\)
\(\frac{{30}\times{t_o}}{{7}{60}}\) = \(\sqrt{\frac{71}{32}}\)
\(\frac{t_c}{14}\) = 1.489
t\(_c\) = 14 x 1.489
t\(_c\) = 20.846
t\(_c\) = 21s
Source: Myschool Past Questions Archive (Record #13779)
Chemistry
UTME / JAMB 1997
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
200 cm3 of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm3. Estimate the percentage of oxygen in the air?
A
31%
B
27%
C
21%
D
19%
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Volume of O2 used = 200 - 158 = 42 cm3
% of O2 = (42)/(200) x 100% = 21%
Source: Myschool Past Questions Archive (Record #13785)
Chemistry
UTME / JAMB 1997
Nature of Matter & Separation Techniques
Solution
On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO4. yH2O. The value of y is?
(Mg = 24, S = 32, O = 16, H = 1)
A
1
B
3
C
5
D
7
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
MgSO4. YH2O
120g (MgSo4) contains - 18g (water)
20g contain (41 - 20g) water.
120g → 18 y; 20 → 21
∴ 18 y = (126)/(18) = 7
Source: Myschool Past Questions Archive (Record #13789)
Chemistry
UTME / JAMB 1997
Non-Metals & Their Compounds
Solution
Which of the following gases is the most dangerous pollutant?
A
Hydrogen sulphide
B
Carbon (lV) oxide
C
Sulphur (lV) oxide
D
Carbon (ll) oxide
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Carbon monoxide is a colourless, odourless and tasteless gas that is produced by the incomplete combustion of fossil fuel. It is the most dangerous of all the pollutant gases and can cause death in very high concentrations.
Source: Myschool Past Questions Archive (Record #13790)
Chemistry
UTME / JAMB 1997
Water, Solutions & Solubility
A saturated solution of AgCl was found to have a concentration of 1.30 x 10-5 mol dm-3. The solubility product of AgCl therefore is?
A
1.30 x 10-5 mol2 dm-6
B
1.30 x 10-7 mol2 dm-6
C
1.69 x 10-10 mol2 dm-6
D
2.60 x 10-12 mol2 dm-6
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 #13800)
Chemistry
UTME / JAMB 1997
Stoichiometry, Mole Concept & Volumetric Analysis
The hydroxyl ion concentrated, (OH-), in a solution of sodium hydroxide of pH 10.0 is?
A
10-10 mol dm-3
B
10-6 mol dm-3
C
10-4 mol dm-3
D
10-2 mol dm-3
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 #13802)
Chemistry
UTME / JAMB 1997
Acids, Bases, pH & Salts
Solution
Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals?
A
13.0
B
7.0
C
6.5
D
3.0
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
pH 13 is strongly basic, pH 7 is neutral, pH 6.5 is slightly acidic but not as strong enough to react vigorously with Mg. However, a pH of 3.0 is sufficiently acidic to react with magnesium and produce hydrogen gas.
Source: Myschool Past Questions Archive (Record #13803)
Chemistry
UTME / JAMB 1997
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Given that 15.00 cm3 of H2
SO4 was required to completely neutralize 25.00 cm3 of 0.125 mol dm-3 NaOH, calculate the molar concentration of the acid solution:
A
0.925 mol dm-3
B
0.156mol dm-3
C
0.104 mol dm-3
D
0.023 mol dm-3
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
H2SO4 + 2NaOH → Na2SO4 + 2H2O
(MaVa)/(MBVB) (1)/(2) (MA x 15)/(0.125 x25) = 1/2
MA = 0.104
Source: Myschool Past Questions Archive (Record #13812)
Chemistry
UTME / JAMB 1997
Electrolysis & Electrochemical Cells
When platinum electrodes are used during the electrolysis of copper (ll) tetraoxosulphate (lV) solution, the solution gets progressively?
A
acidic
B
basic
C
neutral
D
amphoteric
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 #13814)
Chemistry
UTME / JAMB 1997
Electrolysis & Electrochemical Cells
Solution
How many Faraday of electricity are required to deposit 0.20 mole of nickel, if 0.10 Faraday of electricity deposited 2.98g of nickel during electrolysis of its aqueous solution?
(Ni = 58.7, 1F = 96 500 C mol-)
A
0.20
B
0.30
C
0.40
D
0.50
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No of mole → (2.98)/(58.7) ..............0.1
2.0 .................x
∴ x = (0.2)/(2.98) x 58.7 x 0.40
Source: Myschool Past Questions Archive (Record #13820)
Chemistry
UTME / JAMB 1997
Oxidation, Reduction & Redox Reactions
What is the oxidation number of Z in K3ZCl6?
A
-3
B
+3
C
-6
D
+6
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 #13822)
Chemistry
UTME / JAMB 1997
Oxidation, Reduction & Redox Reactions
2H2S(g) + SO2(g) + H2O(I) → 3S(s) + 3H2O(I)..........(i) 3CuO(s) + 2NH3(g) → 3Cu(s) + 3H2O(I) + N2(g).........(II) In the equations above, the oxidizing agent (I) and the reducing agent in (II) respectively are?
A
H2S and NH3
B
SO2 and CuO
C
SO2 and NH3
D
H2S and CuO
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 #13827)
Chemistry
UTME / JAMB 1997
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
2SO2(g) + O2(g) → 2SO3. In the reaction above, the standard heats of formation of SO2(g) and SO3(g) are -297 KJ mol-1 and -396 kJ/mol respectively. The heat change of the reaction is?
A
-99 kJ mol-
B
-198 kJ mol-
C
+198 kJ mol-
D
+683kJ mol-
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
2SO2 + O2 → 2SO3
2(-297) 2(-396)
-594 -792
Heat change = heat of product - heat of reactants = -792 - (-594) = -198kj mol-
Source: Myschool Past Questions Archive (Record #13828)
Chemistry
UTME / JAMB 1997
Reaction Rates & Chemical Equilibrium
If the rate law obtained for a given reaction is rate = k(X)n (Y)m, what is the overall order of the reaction?
A
nm
B
n/m
C
n + m
D
n - m
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 #13829)
Chemistry
UTME / JAMB 1997
Chemical Energetics & Thermochemistry
One method of driving the position of equilibrium of an endothermic reaction forward is to?
A
increase temperature at constant pressure
B
dcrease pressure at constant temperature
C
cool down the apparatus with water
D
decreases temperature at constant pressure
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 #13830)