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Physics
WAEC / WASSCE 2010
Current Electricity & Electric Circuits
Solution
You are provided with a voltmeter V, a chemical cell/ battery E; two standard resistors R, and R a potentiometer a key K a jockey, and other necessary materials.
Set up a circuit as shown in the diagram above.
Close the key K.
Make contact with the potentiometer wire AB using the jockey at a point C such that AC = x = 20cm
Read and record the voltmeter reading
Evaluate x\(^{-1}\) and v\(^{-1}\)
Repeat the procedure for other values of x= 30, 40, 50, 60 and 80cm.
Tabulate your readings.
Plot a graph with V\(^{-1}\) on the vertical axis and x\(^{-1}\) on the horizontal axis, starting both axes from the origin (0, 0).
Determine the:
(a) slope, s, of the graph;
(b) intercept, c, on the vertical axis.
State two precautions taken to ensure accurate results.
(b)i. State the two devices in which ohm's law does not apply.
ii. A current of 1 A is supplied to two resistors of resistance 2\(\Omega\) and 3\(\Omega\) connected in parallel. Calculate the current in each resistor.
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
x/cm
v/volt
x\(^{1}\)/cm\(^{-1}\)
v\(^{1}\)/volts\(^{-1}\)
20
0.15
0.050
6.667
30
0.20
0.033
5.000
40
0.30
0.025
3.333
50
0.40
0.020
2.500
60
0.50
0.016
2.000
80
0.60
0.013
1.667
Slope = \(\frac{6.667-1.667}{0.050-0.013} = \frac{5}{0.037}\)
= 135.135cm/volt
intercept = 0
Precautions;
- Tight connections /clean terminals was ensured
- Key removed when readings are not being taken.
- Parallex error avoided in reading voltmeter/ rule.
- Zero error noted and corrected for in the voltmeter/rule
- Dragging jockey along the wire avoided
Source: Myschool Past Questions Archive (Record #60018)
Chemistry
UTME / JAMB 2010
Chemical Bonding & Intermolecular Forces
Solution
Which of the following salts is slightly soluble in water?
A
AgCl
B
CaSO4
C
Na2CO3
D
PbCl2
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The salt that is slightly soluble in water is CaSO\(_4\) (Calcium Sulfate).
AgCl (Silver Chloride): This is considered very slightly soluble or nearly insoluble in water due to its strong ionic bonds.
Na\(_2\)CO\(_3\) (Sodium Carbonate): This is highly soluble in water as it is a sodium salt.
PbCl\(_2\) (Lead Chloride): While considered slightly soluble, it has a lower solubility compared to CaSO4.
Source: Myschool Past Questions Archive (Record #4482)
Chemistry
UTME / JAMB 2010
Non-Metals & Their Compounds
Solution
In the preparation of oxygen by heating KClO\(_3\) in the presence of MnO\(_2\), only moderate heat is needed because the catalyst acts by?
A
lowering the pressure of the reaction
B
increasing the surface area of the reactant
C
increase the rate of the reaction
D
lowering the energy barrier of the reaction
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
In the thermal decomposition of potassium chlorate ((KClO\(_3\) ), manganese(IV) oxide (MnO\(_2\)) acts as a catalyst. A catalyst functions by providing an alternative reaction pathway with a lower activation energy (the "energy barrier"). Because this barrier is lowered, more reactant particles possess sufficient kinetic energy to undergo successful collisions at a lower temperature, allowing the reaction to proceed efficiently with only moderate heat.
While option C is also a characteristic of catalysts, option D specifically explains how the catalyst enables the use of moderate heat rather than the high temperatures required for the uncatalyzed reaction
Source: Myschool Past Questions Archive (Record #4489)
Chemistry
UTME / JAMB 2010
Non-Metals & Their Compounds
Solution
In the diagram above, the gas produced is?
A
NO
B
NO2
C
N2O
D
N2O4
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
In the laboratory, nitrogen monoxide (NO), also known as nitric oxide, is commonly prepared by the reduction of dilute nitric acid with copper, resulting in the formation of copper(II) nitrate, water, and nitrogen monoxide gas.
The chemical equation for this reaction is: 4HNO\(_3\) + Cu → Cu(NO\(_3\))\(_2\) + 2NO + 4H\(_2\)O
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following equations represents beta decay?
A
\(\frac{14}{7}\)N + \(\frac{4}{2}\)He → \(\frac{8}{17}\)O + \(\frac{1}{1}\)H
B
\(\frac{8238}{92}\)U → \(\frac{234}{90}\)Th + \(\frac{4}{2}\)He
C
\(\frac{8238}{92}\)U → \(\frac{239}{93}\)Np + \(\frac{0}{-1}\)e
D
\(\frac{13}{7}\)N + \(\frac{4}{2}\)He → \(\frac{16}{8}\)O + \(\frac{1}{1}\)H
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 #37433)
Chemistry
WAEC / WASSCE 2010
Periodic Table & Periodicity
The energy change which accompanies the addition of an electron to a gaseous atom is
A
atomization
B
electron affinity
C
electronegativity
D
ionization
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 #37434)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following elements is a d-block element?
A
Calcium
B
lron
C
Lithium
D
Silicon
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 #37435)
Chemistry
WAEC / WASSCE 2010
Non-Metals & Their Compounds
Which of the following statements about chlorine and iodine at room temperature is correct?
A
Chlorine is gas and iodine is solid
B
Chlorine is liquid and iodine is gas
C
Chlorine and iodine are gases
D
Chlorine is solid and iodine is liquid
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 #37439)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
If X is a group lll element, its oxide would be represented as
A
X3O2
B
X3O
C
X2O3
D
XO3
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 #37440)
Chemistry
WAEC / WASSCE 2010
Atomic Structure, Orbitals & Nuclear Chemistry
Which of the following species correctly represented an ion of M with 13 protons and 10 electrons?
A
10M 3+
B
10M 3-
C
13M 3+
D
13M 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 #37441)
Chemistry
WAEC / WASSCE 2010
Chemical Bonding & Intermolecular Forces
A solid substance with high melting and boiling points is likely to be a/an
A
covalent compound
B
dative covalent compound
C
electrovalent compound
D
non-metal
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 #37445)
Chemistry
WAEC / WASSCE 2010
Chemical Bonding & Intermolecular Forces
Which of the following molecules has a linear shape?
A
CH4
B
CO 2
C
H2S
D
NH 3
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 #37446)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following molecules has a triple bond in its structure?
A
CH4
B
NH3
C
N2
D
O 2
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 #37447)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Consider the neutralization reaction represented by the following equation: Na2CO3 + 2HNO 3 → 2NaNO3 + H2O + CO2 The stoichiometric ratio of acid to base is
A
2:2
B
2:1
C
1:2
D
1:1
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The mole ratio of acid to base = 2:1
Source: Myschool Past Questions Archive (Record #37456)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
A solution of sodium trioxocarbonate (IV) contains 10.6g in 250cm3 of solution. Calculate the concentration of the solution. [Na2CO3 = 106.0]
A
0.4 mol dm-3
B
1.0 mol dm-3
C
10.6 mol dm-3
D
25.0 mol dm-3
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 #37457)