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Physics
UTME / JAMB 1995
Current Electricity & Electric Circuits
Solution
The primary winding of a transformer has 400 turns and its secondary has 100 turns. If a source of e.m.f. of 12V is applied to the primary, the secondary e.m.f. will be
A
3V
B
6V
C
24V
D
48V
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
\(\frac{V_s}{V_p}\) = \(\frac{N_s}{N_p}\) = \(\frac{I_p}{I_s}\)
\(\frac{100}{400}\) = \(\frac{V_S}{12}\)
V = 3V
Source: Myschool Past Questions Archive (Record #27856)
Physics
UTME / JAMB 1995
Atomic, Quantum, Nuclear Physics & Electronics
Solution
A light of energy 5eV falls on a metal and the electrons with a maximum kinetic energy of 2eV are ejected. The work function of the metal is
A
0.4eV
B
2.5eV
C
3.0eV
D
7.0eV
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Work function = 5 - 2
= 3eV
Source: Myschool Past Questions Archive (Record #27857)
Physics
UTME / JAMB 1995
Electrostatics & Capacitors
Solution
The resultant capacitance in the fig above is
A
15.0µF
B
9.8µF
C
1.3µF
D
0.8µF
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Capacitors in parallel = 4\(\mu\)f + 2 \(\mu\) f = 6\(\mu\) f
Capacitors in series =\(\frac{1}{C_{eff}}\) = \(\frac{1}{C_1} + \frac{1}{C_2} + \frac{1}{C_3} + \frac{1}{C_4}\)
\(\frac{1}{C_{eff}}\) = \(\frac{1}{2} + \frac{1}{3} + \frac{1}{6} + \frac{1}{4}\) = \(\frac{6 + 4 + 2 + 3}{12}\)
\(\frac{1}{C_{eff}}\) = \(\frac{15}{12}\)
C\(_{eff}\) = \(\frac{12}{15}\) = 0.8\(\mu\) f
Source: Official Exam / Past Question Archive
Physics
UTME / JAMB 1995
Atomic, Quantum, Nuclear Physics & Electronics
The half-life of a radio-active element is 9 days, what fraction of atoms has decayed in 36 days?
A
\( \frac{1}{16} \)
B
\( \frac{1}{4} \)
C
\( \frac{1}{2} \)
D
\( \frac{15}{16} \)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #41542)
Physics
UTME / JAMB 1995
Magnetism, Electromagnetism & AC Circuits
An alternating source is connected in series to a capacitor of capacity reactance \( 10^3 \sqrt{3} \) and a resistor of resistance 103 Ohms. The Impedance of the circuit is...
A
\( 2000 \sqrt{3} \) Ohms
B
2000 Ohms
C
\( 1000 \sqrt{3} \) Ohms
D
1000 Ohms
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #41543)
Physics
UTME / JAMB 1995
Current Electricity & Electric Circuits
Diagram
Solution
The value of T in the figure above is
Attached Figure / Diagram
A
10.0N
B
11.8N
C
20.0N
D
40.0N
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
The total upward vertical force must balance the downward weight of 20 N.
There are two vertical components:
2 \times (T \times sin(30^\circ)) = 20 N
Sin(30^\circ) = \(\frac{1}{2}\) = 0.5
So:
2 \times T \times 0.5 = 20
T = 20
Source: Myschool Past Questions Archive (Record #41728)
Physics
UTME / JAMB 1995
Current Electricity & Electric Circuits
Diagram
Solution
The acceleration of the system show above is
Attached Figure / Diagram
A
2ms-2
B
4ms-2
C
6ms-2
D
8ms-2
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
M\(_2\)g - M\(_2\)a = M\(_1\)a + M\(_1\)g Sin\(\theta\)
(30 x 10) - 30a = 20a + 20 x 10 x Sin 30
300 - 30a = 20a + 100
- 30a - 20a = 100 - 300
- 50a = - 200
a = \(\frac{-200}{-50}\) = 4m/s\(^2\)
Source: Myschool Past Questions Archive (Record #41729)
Physics
UTME / JAMB 1995
Newton's Laws, Momentum & Collisions
Diagram
Solution
A body of mass 40kg is being dragged along the floor by a rope inclined at 60 degrees to the horizontal. The frictional force between the box and the floor is 100N and the tension on the rope is 300N. How much work is done by dragging the box for a distance of 4m
Attached Figure / Diagram
A
680J
B
400J
C
200J
D
100J
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Force required to move the object forward = Fcos 60 = 300 x 0.5 = 150N
Frictional Force = 100N
Total force acting on the object = 150 - 100 = 50N
Work Done = Total force x distance = 50 x 4 = 200J.
Source: Myschool Past Questions Archive (Record #41730)
Physics
UTME / JAMB 1995
Current Electricity & Electric Circuits
Diagram
Solution
The fig above shows two similar bulbs X and Y connected to suitable power supply with F as an appropriate fuse rating, if the filament of X breaks then the
Attached Figure / Diagram
A
Brightness Of Y will reduce
B
Brightness Of Y will remain constant
C
Brightness Of Y will increase
D
fuse F will blow
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Diagram above shows a Parallel circuit
If one of the parallel path is broken, current will continue to flow in other parts.
Voltage is the same across each component of the parallel circuit.
The brightness of a light bulb is given by its power. P = I\(^2\)R,
and so brightness depends on current and resistance.
Hence; the brightness of Y will not be affected except for a variation in resistance property.
Source: Myschool Past Questions Archive (Record #41731)
Chemistry
UTME / JAMB 1995
Nature of Matter & Separation Techniques
Solution
Chromatography is used to separate components of mixtures which differ in their rates of?
A
diffusion
B
migration
C
reaction
D
sedimentaion
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Chromatography is a technique that separates the components of a mixture based on their different rates of migration through a stationary phase and a mobile phase.
Mobile phase: The moving part of the chromatography setup.
Stationary phase: The non-moving part of the chromatography setup.
The rate at which a component moves through the chromatography setup depends on how well it absorbs to the stationary phase and how soluble it is in the mobile phase.
Source: Myschool Past Questions Archive (Record #13604)
Chemistry
UTME / JAMB 1995
Nature of Matter & Separation Techniques
Which of the following is a example of a chemical change?
A
Dissoultion of salt in water
B
Rusting of iron
C
Melting of ice
D
Separating a mixture by distillation
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 #13613)
Chemistry
UTME / JAMB 1995
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
The number of hydrogen ions in 4.9 g of tetraoxosulphate (IV) acid is?
(S = 32, O =16, H = 1, Avogadro Number = 6.02 x 10\(^{23}\) )
A
3.01 x 1022
B
6.02 x 1022
C
3.01 x 1023
D
6.01 x 1023
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
First write a dissociation equation: H\(_2\)SO\(_4\) ⇌ 2H\(^+\) + SO\(_4\)\(^{2-}\)
Number of moles = \(\frac{Number of ions}{Avogadro number}\)
But we need to get the number of moles first by applying n = \(\frac{m}{M}\)
n = \(\frac{4.9}{98}\) (Molar mass of H\(_2\)SO\(_4\) = 98g/mol)
n = 0.05 mole
Number of moles = \(\frac{Number of ions}{Avogadro number}\)
Number of hydrogen ions = ( n x L ) X 2 → We multiplied by 2 because 2H\(^+\) were formed.
= 0.05 x 2 x 6.02 x 10\(^{23}\)
= 6.02 x 10\(^{22}\) ions
Source: Myschool Past Questions Archive (Record #13615)
Chemistry
UTME / JAMB 1995
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
What volume of oxygen will remain after reacting 8cm\(^3\) of hydrogen with 20cm\(^3\) of oxygen?
A
10 cm3
B
12 cm3
C
14 cm3
D
16 cm3
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
First write a balanced equation for the chemical reaction:
2H\(_2\) + O\(_2\) → 2H\(_2\)O
Mole ratio: 2 moles : 1 mole
Expected reacted volume: 8 cm\(^3\) : 20 cm\(^3\)
Actual reacted volume: 8 cm\(^3\) : 4 cm\(^3\)
Residual Volume(Expected - Actual): 0 : 16 cm\(^3\)
Therefore, the volume of oxygen remaining is 16 cm\(^3\)
Source: Myschool Past Questions Archive (Record #13618)
Chemistry
UTME / JAMB 1995
Stoichiometry, Mole Concept & Volumetric Analysis
A gas sample with an initial volume of 3.25 dm3 is heated and allowed to expand to 9.75 dm3 at constant pressure. What is the ratio of the final absolute temperature to the initial absolute temperature?
A
3:1
B
5:2
C
5:4
D
8:3
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 #13621)
Chemistry
UTME / JAMB 1995
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
Two cylinders A and B each contains 30 cm\(^3\) of oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?
A
3.2 g
B
6.4 g
C
80.0 g
D
160.0 g
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Avogadro's Law states that, at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of gas. In simpler terms, equal volumes of different gases contain the same number of molecules when they are at the same temperature and pressure.
Since both Oxygen and Nitrogen contain the same volume of gases at the same temperature and pressure, their number of moles will also be the same. i.e If Nitrogen contains 5.0 moles, then Oxygen will also contain 5.0moles.
Thus, number of moles of oxygen, n = 5.0 moles
Molar mass of O\(_2\) = 16 x 2 = 32g/mol
But n = \(\frac{m}{M}\)
m = n x M = 5 X 32 = 160.0g
Source: Myschool Past Questions Archive (Record #13623)