Question Library
Browse, filter, and study verified past examination questions with step-by-step mathematical reasoning.
Searching 18,000+ Questions...
Sifting topics, KaTeX formulas & verified solutions
Showing 6196–6210 of 29821 verified questions
Sort by:
Physics
WAEC / WASSCE 2018
Calorimetry, Latent Heat & Change of State
Solution
(a) List two factors each that affect heat loss by:
(i) radiation;
(ii) convection.
(b) State two factors that determine the quantity of heat in a body.
(c) Explain the statement: The vecilic latent heat of vaporization of mercury is 2.72 x 10\(^5\) Jkg\(^{-1}\).
(d)A jug of heat capacity 250 Jkg\(^{-1}\) contains water at 28^\circC. An electric heater of resistance 35\(\Omega\) connected to a 220 V source is used to raise the temperature of the water until it boils at 100^\circC in 4 minutes. After. another 5 minutes, 300 g of water has evaporated. Assuming no heat is lost to the surroundings, calculate the:
(i) mass of water in the jug before heating;
(ii) specific latent heat of vaporization of steam. [Specific heat capacity of water = 4200 kg\(^{-1}\)K\(^{-1}\)]
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
(a) (i) Radiation:
Surface area, Temperature.
(ii) Convection:
Nature, Density/Viscosity of the fluid, Thermal conductivity of fluid, Specific heat capacity of fluid and Exposed surface area.
(b) Factors that determine the quantity of heat in a body: Heat/thermal capacity and. Temperature
(c) It means that 2.72 x 105J of heat energy is required/ needed to change I kg of mercury at its boiling point to vapour (without temperature change)
(d) (i) heat supplied by heater = ivt = \(\frac{v^2}{R}\)t
heat gained by water = M\(_w\)C\(_w\)(\(\theta_2\) - \(\theta_1\))
where M\(_w\) = mass of water
C\(_w\) = s.h.c of water
\(\theta_2\) = final temp. of water
\(\theta_1\) = initial temp. of water
Heat gained by jug = C\(_j\) (\(\theta_2\) - \(\theta_1\))
\(\frac{v^2t}{R}\) = M\(_w\)C\(_w\) (\(\theta_2\) - \(\theta_1\))
= \(\frac{220^2 \times 4 \times 60}{35}\)
= M\(_w\) x 4200[100 - 28] + 250[100 - 28]
M\(_w\) = 1.038kg
Source: Myschool Past Questions Archive (Record #52871)
Physics
WAEC / WASSCE 2018
Waves, Sound & Vibrations
Solution
(a) Define dffraction.
(b)(i) Explain critical angle. The diagram here illustrates a ray of light passing through a rectangular transparent plastic block \(\alpha\) Determine the value of the critical angle. \(\beta\) Calculate the refractive index of the block.
(c) A pipe closed at one end has fundamental frequency of 200Hz. The frequency of the first overtone of the closed pipe is equal to the frequency of the first overtone of an open pipe. Calculate the:
(i) fundamental frequency of the open pipe;
(ii) length of the closed pipe;
(iii) length of the open pipe. [Speed of sound in air = 330 ms\(^{-1}\)]
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
(a) Diffraction is the bending or spreading of a wave round an obstacle or as it passes through an opening.
(b) (i) Critical angle is the angle of incidence in the denser medium when an angle of refraction in the lens dense medium is 90^\circ.
(ii) (\(\alpha\))Critical angle = 90^\circ -.44^\circ = 46^\circ
(\(\beta\))n = \(\frac{1}{sin c} = \frac{1}{\sin 46^o}\) = 1.39
(c) (i) Closed Pipe
1st Overtone = 3f\(_o\) = 3 x 200 = 600Hz
Open Pipe
All harmonics are possible overtone = 2f\(_o\)
2f\(_o\) = 600
f\(_o\) = 300Hz
(ii) Closed Pipe
f\(_o\) = \(\frac{v}{4l}\)
l = \(\frac{v}{4f_o}\)
\(\frac{330}{4 \times 200}\)
= 0.412m
Open Pipe
\(f_1\) = \(\frac{v}{l}\)
600 = \(\frac{300}{l}\)
l = 0.55m
or
\(f_1\) = \(\frac{v}{2l}\)
300 = \(\frac{300}{2 \times l}\)
l = \(\frac{330}{600}\)
= 0.55m
Source: Myschool Past Questions Archive (Record #52872)
Physics
WAEC / WASSCE 2018
Current Electricity & Electric Circuits
Solution
(a) Define:
(i) reactance;
(ii) impedance in an a.c.
The diagram here illustrates an a.c. generator. When the coil is rotated, an e.m.f is induced in the coil.
(i) Explain why an e.m.f. is induced.
(ii) State the purpose of the slip-rings.
(iii) Name and state the law used to determine the direction of the induced current.
(iv) State two ways to increase the induced e.m.f.
(c) A lamp is rated 12 V. 6 W. Calculate the amount of energy transformed by the lamp in 5 minutes.
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
(a)(i) Reactance is the opposition to the flow of a.c offered by a capacitor or an inductor or both.
(ii) Impedance is the overall opposition of a mixed circuit containing a resistor, an inductor and/or a capacitor.
(b) (i) Emf is induced because the coil rotates at a steady speed about a fixed axis in the magnetic field of the elctromagnet, it cuts through the magnetic lines of force.
(ii) The direction of current is reversed in each half of the rotation of the coil.
(iii) The law used to determine the direction of the induced current is Lenz's law. It states that the direction of the induced current is such as to oppose the change producing it.
(iv) The induced e.m.f can be increased by any two of the following: increased speed of rotation, efficient core design, increased number of turns in the coil and increased area of coil.
(c) E = Power x Time
= 6 x 5 x 60
=1800J
Source: Myschool Past Questions Archive (Record #52873)
Physics
WAEC / WASSCE 2018
Atomic, Quantum, Nuclear Physics & Electronics
Solution
(a) Define binding energy in an atom.
(b) List three evidence to support the claim that X-rays are electromagnetic waves.
(c) List three peaceful uses of nuclear energy.
(d) Light of wavelength 4.5 x 10\(^{-7}\) in is incident on a metal resulting in the emission of photo electrons. If the work function of the metal is 3.0 x 10\(^{-9}\) J, calculate the:
(i) frequency of the incident light;
(ii) energy of the incident light;
(iii) energy of the photoelectrons. [Speed of light = 3.0 x 10\(^8\) ms\(^{-1}\), h = 6.6 x 10\(^{-34}\) Js]
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
(a) Binding energy is the minimum energy required to seperate the nucleus of an atom.
(b) Three evidences in support of the claim that x -rays are electromagnetic waves are:
(i) They can be polarized.
(ii) They can travel through a vacuum.
(iii) They travel with the speed of light.
(iv) They are not affected by electric field.
(v) They are not affected by magnetic field.
(c) Three peaceful uses of nuclear energy are:
(i) It is used in the treatment of tumour.
(ii) It is used to power submarines.
(iii) It is used to generate electricity.
(d) (1) c = f\(\lambda\) or f = \(\frac{c}{\lambda}\)
f = \(\frac{3.0 \times 10^8}{4.5 \times 10^{-7}}\)
f = 6.67 x10\(^{14}\)Hz
(ii) E = hf
= 6.67 x10\(^{-34}\) x 6.67 x10\(^{14}\)J
= 4.4 x10\(^{-19}\)J
(iii) K.E = E- W
= 4.4 x 10\(^{-19}\)
=1.4 x 10\(^{-19}\) - 3.0 x 10\(^{-19}\)
=1.4 x 10\(^{-19}\)J
Source: Myschool Past Questions Archive (Record #52874)
Physics
UTME / JAMB 2018
Reflection, Refraction & Dispersion of Light
Solution
The critical angle for light traveling from a transparent medium to air s measured as 34º. The refractive index of the medium is
A
0.56
B
1.50
C
1.79
D
2.02
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
N = \(\frac{1}{sin\theta}\)
= \(\frac{1}{sin34}\)
= 1.79
Source: Official Exam / Past Question Archive
Physics
WAEC / WASSCE 2018
Current Electricity & Electric Circuits
Solution
You are provided with an ammeter, a resistor, key, metre bridge, and other necessary apparatus.
i. Connect a circuit as shown in the diagram above.
ii. Close the key and use the jockey to make contact with AB at N such that AN = d = 25cm
iii. Read and record the ammeter reading.
iv. Evaluate 1\(^{-1}\).
v. Repeat the procedures for values of d = 35cmm, 50cm, 65cm and 80cm. In each case, record I and determine 1\(^{-1}\)
vi. Tabulate your results.
vii. Plot a graph with log on the vertical axis and d on the horizontal axis.
viii. Determine the slope, s of the graph.
ix. State two precautions taken to obtain accurate results.
(b)i. Use your graph to determine the value of d = l = 1.5A.
ii. State two factors that affect the resistance of a wire.
A
0.5
B
0.8
C
1.2
D
1.5
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
S/N
d(cm)
I(A)
I\(^{1}\)(A\(^{-1}\))
Log I\(^{-1}\)
1
25
0.65
1.54
0.19
2
35
0.55
1.82
0.26
3
50
0.44
2.50
0.40
4
65
0.30
3.33
0.52
5
80
0.23
4.35
0.64
vii. Scale: 2cm to 10 units on x-axis
2cm to 0.1 unit on y-axis
viii. Slopes(s) = \(\frac{x_{2} - x_{1}}{y_{2} - y_{1}}\)
= \(\frac{80 -25}{0.64 - 0.20}\)
= \(\frac{55}{0.44}\)
= 125
(ix) Precautions
(a) Key opened in between reading or keys opened when readings were not taken
(b) Tight connections ensured
(c) Avoided parallax error when taking reading on ammeter or metre rule
(d) Repeated readings shown
(e) Avoided zero error on ammeter or metre rule
(f) Clean terminals ensured.
(b)i. 1\(^{-1}\) = \(\frac{1}{1.5}\)
= 0.67
Log(1\(^{-1}\)) =-0.174
ii. Factors affecting the resistance of a wire
- Length of wire
- Cross-sectional area/ thickness/ diameter/ radius of wire
- Resistivity or nature of wire
- Temperature.
Source: Official Exam / Past Question Archive
Physics
WAEC / WASSCE 2018
Circular Motion, Gravitation & Simple Harmonic Motion
Diagram
Solution
You are provided with a pendulum bob, a metre rule, a stopwatch, a retort stand with clamp, and other necessary apparatus.
i. Suspend the pendulum bob from the clamp as illustrated in the diagram.
ii. Adjust the pendulum such that AC=L= 90 cm
iii. Displace the pendulum bob slightly such that it oscillates in a vertical plane.
iv. Measure and record the time t for 20 complete oscillations.
v. Evaluate T and \(\sqrt L\)
vi.Repeat the procedure for four others values of L= 80 cm,70 cm, 60 cm, and 50cm.
vii. Tabulate your readings
viii. Plot a graph with T on the vertical axis and \(\sqrt L\) on the horizontal axis.
ix. Determine the slope, s, of the graph.
x. Evaluate g= \(\frac{4\pi^{2}}{5^{2}}\)
xi. State two precautions taken to ensure accurate results.
(b) i. Determine from your graph, the period of the pendulum for L= 75 cm.
ii. A simple pendulum bob is set into simple harmonic motion. Sketch a diagram of the setup and indicate on it; the positions of:
(a) maximum velocity.
(b) maximum acceleration of the bob
Attached Figure / Diagram
medium Difficulty
Verified Correct Answer: Option
Physical Principles & Numerical Solution
S/N
L(cm)
t(s)
T = \(\overline{20}\)(S)
\(\sqrt L\)
1
90
38
1.90
9.49
2
80
36
1.80
8.94
3
70
34
1.70
8.37
4
60
32
1.50
7.73
5
50
30
1.50
7.07
viii. Scale: 2cm rep 0.05 unit on y-axis
2cm rep 1.0 unit on x-axis
ix. Slopes(s) = \(\frac{X_2 - X_1}{Y_2 - Y_1}\)
= (\(\frac{9.9 - 5.7}{2.0 - 1.25}\))
= \(\frac{4.2}{0.75}\)
= 5.6cm
x. Evaluate g = \(\frac{4\pi{^2}}{5^{2}}\)
= \(\frac{4(3.143)^{2}}{(5.6)^{2}}\)
= \(\frac{9.878}{31.36}\)
= 0.315
xi. Precuations:
i. Avoided zero error on stop clock/ metre rule.
ii. Avoided draught.
iii. Avoided conical oscillation
iv. Ensured that support was rigid or firm
v. Ensured bob/pendulum was free from table.
(b)i. \(\sqrt{75cm}\) = 8.66
ii.
Source: Myschool Past Questions Archive (Record #59880)
Chemistry
UTME / JAMB 2018
Kinetic Theory of Matter & Gas Laws
According to Charles' law, the volume of a gas becomes zero at
A
0°C
B
-100°C
C
-273°C
D
-373°C
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 #47285)
Chemistry
UTME / JAMB 2018
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
A substance that is used as a ripening agent for fruits is
A
ethene
B
propane
C
methane
D
butane
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 #47286)
Chemistry
UTME / JAMB 2018
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
The Sulphide which is insoluble in dilute hydrochloric acid is
A
FeS
B
CuS
C
ZnS
D
Na2S
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Sulphides like PbS (lead (II) sulphide) and CuS (copper (II) sulphide) are insoluble in acidified solutions.
Source: Myschool Past Questions Archive (Record #47287)
Chemistry
UTME / JAMB 2018
Stoichiometry, Mole Concept & Volumetric Analysis
An element used in the production of matches is
A
nitrogen
B
aluminium
C
copper
D
sulphur
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 #47294)
Chemistry
UTME / JAMB 2018
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following gases may not be dried with concentrated sulphuric acid?
A
HCl\(_{(g)}\)
B
NH\(_3\)
C
Cl\(_2\)
D
SO\(_2\)
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 #47296)
Chemistry
UTME / JAMB 2018
Organic Chemistry I: Hydrocarbons & Crude Oil
The Consecutive members of an alkane homologous series differ by
A
CH
B
CH\(_2\)
C
CH\(_3\)
D
C\(_n\)H\(_n\)
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 #47314)
Chemistry
UTME / JAMB 2018
Electrolysis & Electrochemical Cells
A correct electrochemical series can be obtained from Na, Ca, Al, Mg, Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging
A
Al and Mg
B
Zn and Fe
C
Zn and Pb
D
Pb and H
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 #47316)
Chemistry
UTME / JAMB 2018
Kinetic Theory of Matter & Gas Laws
Solution
A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that
A
collisions are perfectly elastic
B
forces of repulsion exist
C
forces of repulsion and attraction are in equilibrium
D
collisions are inelastic
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
According to one of the kinetic theories of gases, When collisions occur, the molecules lose no kinetic energy; that is, the collisions are said to be perfectly elastic.
Source: Myschool Past Questions Archive (Record #47317)