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Chemistry
UTME / JAMB 2007
Electrolysis & Electrochemical Cells
How long would it take to deposit 0.08g of copper from CuCl\(_2\) solution by passing a current of 0.5A?
[Cu = 64, 1F = 96500 C mol-1]
A
6 mins
B
8 mins
C
24 mins
D
48 mins
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 #3813)
Chemistry
UTME / JAMB 2007
Metals, Transition Elements & Extraction
Solution
Tartaric acid is used industrially to
A
make baking powder
B
make fruit juices
C
remove rust
D
dry substance
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Tartaric acid is used industrially as an acidulant in food products like carbonated drinks, jellies, and baking powder, as well as in metal cleaning and polishing processes due to its chelating properties; it also finds applications in textile processing and certain photographic development procedures.
The major industrial use of tartaric acid is as an acidulant in the food and beverage industry, primarily used to add a tart flavour to products like carbonated drinks, fruit jellies, candies, and wine, often in combination with other acids to achieve the desired taste profile; it is also used as a leavening agent in baking due to its reaction with baking soda when heated.
Source: Myschool Past Questions Archive (Record #3818)
Chemistry
UTME / JAMB 2007
Chemical Energetics & Thermochemistry
Dissolving some pellets of NaOH in water would result in
A
a decrease in the free energy of the solution
B
a decrease in the entropy of the solution
C
a lowering of the temperature of te solution
D
an increase in the entropy of the solution
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 #3822)
Chemistry
UTME / JAMB 2007
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Calculate the number of moles of HCl present in 20cm3 of a 0.75M solution of the acid
A
0.015 mole
B
0.038 mole
C
3.800 moles
D
1.500 moles
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Number of moles = (conc. in mol/dm3*volume in cm3)/1000
(0.75 * 20)/100 = 0.015 mole
Source: Myschool Past Questions Archive (Record #3826)
Chemistry
UTME / JAMB 2007
Oxidation, Reduction & Redox Reactions
Solution
The oxidation state of oxygen in tetraoxosulphate (VI) acid is
A
-4
B
-2
C
+4
D
-8
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
H2SO4
(O.N of hydrogen * 2 ) + O.N of sulphur + O.N of oxygen * 4 = 0
∴ 1 * 2 + 6 + 4x = 0
2 + 6 + 4x = 0
8 + 4x = 0
4x 0 - 8 = -8
4x = -8
x = -8/4 = -2
Source: Myschool Past Questions Archive (Record #3831)
Chemistry
UTME / JAMB 2007
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
MnO\(_2\)(s) + xHCl(aq) → MnCl\(_2\)(aq) + yH\(_2\)O(l) + zCl\(_2\)(g)
In the equation above, what are the values of x, y and z respectively
A
2, 1, 2
B
4, 1, 2
C
4, 2, 1
D
1, 2, 1
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
MnO\(_2\)(s) + xHCl(aq) → MnCl\(_2\)(aq) + yH\(_2\)O(l) + zCl\(_2\)(g)
First, balance the chemical equation, then equate each of the letters with the coefficients.
On balancing, we have : MnO\(_2\)(s) + 4HCl(aq) → MnCl\(_2\)(aq) + 2H\(_2\)O(l) + Cl\(_2\)(g)
Therefore, x = 4,y = 2 and z = 1
Source: Myschool Past Questions Archive (Record #3834)
Chemistry
UTME / JAMB 2007
Kinetic Theory of Matter & Gas Laws
Solution
Calculate the mass of chlorine gas which occupies a volume of 1.12dm3 at s.t.p
[Cl = 35.5, molar volume of gas at s.t.p = 22.4 dm3
A
15.50 g
B
7.10 g
C
3.55 g
D
1.80 g
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
2 * 35.5g of chlorine has a volume of 22.4 dm3 at s.t.p
∴ xg of chlorine will have a volume of 1.12 dm3
x = (1.12 * 35.5 * 2)/22.4 = 3.55g
Source: Myschool Past Questions Archive (Record #3838)
Chemistry
UTME / JAMB 2007
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
Which experiment led to the measurement of the charge on an electron?
A
Mass spectrometric experiment
B
Oil-drop experiment
C
Scattering α - particles
D
Discharge-tube experiment
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
In 1909, Robert Millikan and Harvey Fletcher conducted the oil drop experiment to determine the charge of an electron.
Source: Myschool Past Questions Archive (Record #3841)
Chemistry
UTME / JAMB 2007
Organic Chemistry I: Hydrocarbons & Crude Oil
Solution
What is the volume of oxygen required to burn complete 45 cm\(^3\) of methane at s.t.p?
A
135.0 cm3
B
180.0 cm3
C
45.0 cm3
D
90.0 cm3
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
CH\(_4\)(g) + 2O\(_2\)(g) → 2H\(_2\)O(g) + CO\(_2\)(g)
First, ensure the chemical equation is balanced, stoichiometrically.
i.e CH\(_4\) reacts with 2O\(_2\) in ratio 1 : 2
If 1 mole of CH\(_4\) reacts with 2 moles of O\(_2\)
Then 45 cm\(^3\) CH\(_4\) react with X cm\(^3\) O\(_2\)
i.e 1cm\(^3\) = 2cm\(^3\)
45cm\(^3\)= X cm\(^3\)
X = 45 x 2 = 90 cm\(^3\)
Source: Myschool Past Questions Archive (Record #3844)
Chemistry
UTME / JAMB 2007
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
How many electrons are in the L shell of \(^{31}_{15}\)P?
A
5
B
8
C
18
D
2
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
N.B :
Atomic number = no. of protons = no. of electrons = 15
Orbital configuration of the neutral atom of the element = 2, 8, 5 which represents the shells starting from the first which is K, L, M respectively. i.e
K = 2, L = 8 , M = 5.
Therefore, the L - shell has 8 electrons.
Source: Myschool Past Questions Archive (Record #3845)
Chemistry
UTME / JAMB 2007
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
If the electron configuration of an element is 1S\(^2\) 2S\(^2\)2P\(^5\), how many unpaired electron are there?
A
2
B
8
C
1
D
4
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
When the electrons are drawn out in the orbitals, following the Hund's rule, the diagram above is what will be obtained.
Source: Myschool Past Questions Archive (Record #3849)
Chemistry
UTME / JAMB 2007
Periodic Table & Periodicity
Solution
Which of the following decrease when a given mass of gas is compressed to half its initial volume?
A
Atomic radius of each
B
Average intermolecular distance
C
Frequency of collisions
D
Number of molecules presents
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
When a gas is compressed to half its volume, the average intermolecular distance decreases because the same number of gas molecules are now confined to a smaller space, forcing them closer together, resulting in a smaller average distance between each molecule.
Conversely, when the volume of a gas is reduced, the frequency of collisions between molecules increases; this is because the molecules have less space to move around, leading to more frequent interactions with each other and the container walls.
Source: Myschool Past Questions Archive (Record #3853)
Chemistry
UTME / JAMB 2007
Metals, Transition Elements & Extraction
Solution
A metal X forms two bromides with the formulae XBr2 and XBr3. What type of bonding exists between X and bromine in the bromide?
A
Ionic bonding
B
Metallic bonding
C
Dative bonding
D
Covalent bonding
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
If the metal X forms two bromides with the formulae XBr\(_2\) and XBr\(_3\), it simply means it has variable oxidation number or states which is one of the characteristics of transition metals. This implies X is a metal. However, whenever a metal combines with a non-metal, there is usually a transfer of electrons from the metals to the non-metals, and the type of bond formed is the ionic or electrovalent bond.
Source: Myschool Past Questions Archive (Record #3859)
Chemistry
UTME / JAMB 2007
Nature of Matter & Separation Techniques
Solution
A mixture of petrol and water can be separated through
A
centrifugation
B
distillation
C
the use of separating funnel
D
the use of filter paper
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Petrol and water are immiscible liquids, so the best method of separation of petrol and water is by a separating funnel.
Source: Myschool Past Questions Archive (Record #3860)
Chemistry
UTME / JAMB 2007
Organic Chemistry I: Hydrocarbons & Crude Oil
Solution
Which of the following represents an aromatic compound?
A
C6H5OH
B
C6H12
C
C6H9OH
D
C6H8
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Aromatic compounds are chemical compounds that consist of conjugated planar ring systems accompanied by delocalized pi-electron clouds in place of individual alternating double and single bonds. In a simpler term, aromatic compounds are compounds of Benzene and its derivatives.e.g Benzene, Phenol, Toluene, xylene, anthracene, Naphthalene etc all cyclically conjugated.
The compound in option A is called phenol - a benzene ring with an hydroxyl group (OH) attached to C-1.
Source: Myschool Past Questions Archive (Record #3861)