Welcome to “EXAMRUNZ.COM” For Neco 2025 Expo
 Questions & Answers

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Tuesday 15th July, 2025
Physics (Objective & Essay) 10:00 am -1:00 pm

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2025 NECO PHYSICS ANSWERS

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NECO PHYSICS OBJ!!!

01-10: BCCBEDDDDB
11-20: DDDDABCBCB
21-30: BBCCECDDDE
31-40: ECDEBBDDEB
41-50: AAAADCEEBE
51-60: CBAEBDECAD

COMPLETED ☑️

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THEORY ANSWERS!

(1a)
(i) Drum shell (body)
(ii) Drumhead (membrane)

(1b)
Camera is an optical device that captures and records images on film While A Projector is an optical device that projects enlarged images or videos onto a screen.

(1c)
Given:
Capacity = 263,000 m³
1 barrel = 159,000 m³
Volume in barrels = Capacity / 1 barrel
= 263,000 / 159,000 ≈ 1.65 barrels
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(2a)
Similarity between vectors and scalars:
Both represent physical quantities.

(2b)
A block of mass m slides down an inclined plane at 30° to the horizontal.
Force acting on it along the plane (F) = component of weight along the plane = mg sin θ
Given g = 10 m/s², θ = 30°
So, F = mg sin 30°
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(3a)
(CHOOSE ANY TWO)
(i) Football (kicked in soccer)
(ii) Basketball (thrown towards the hoop)
(iii) Javelin (thrown in athletics)
(iv) Shot put (thrown in athletics)
(v) Discus (thrown in athletics)
(vi) Tennis ball (hit over the net)

(3b)
Given:
Distance (R) = 30 m
Speed (u) = 20 m/s
g = 10 m/s²
To find angle θ for projectile:
Formula for range:
R = (u² sin 2θ) / g
30 = (20² sin 2θ) / 10
30 = (400 sin 2θ) / 10
30 = 40 sin 2θ
sin 2θ = 30 / 40 = 0.75
2θ = sin⁻¹ 0.75 ≈ 48.59°
θ = 48.59° / 2 ≈ 24.3°
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(4a)
Thermocouple is a device made of two different metals joined at two junctions that produces a voltage when there is a temperature difference between the junctions.

(4b)
Given:
Resistance at 0°C (R₀) = 10 Ω
Resistance at 100°C (R₁₀₀) = 15 Ω
Resistance at unknown temperature (R) = 11.5 Ω

Using the linear relation,
R = R₀ + α R₀ T
Where α = temperature coefficient, T = temperature to find.

First find α:
15 = 10 + 10α(100)
15 – 10 = 1000α
5 = 1000α
α = 5 / 1000 = 0.005 per °C

Now let’s find T,
11.5 = 10 + 10(0.005) T
11.5 – 10 = 0.05 T
1.5 = 0.05 T
T = 1.5 / 0.05 = 30°C
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(5a)
It means the effort moves 4 times the distance moved by the load, implying a mechanical advantage of 4.

(5b)
• 50 kg: Mass, the amount of matter in the bag, scalar quantity.

• 500 N: Weight, the force due to gravity acting on the mass (Weight = mass × gravity).
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(6a)
Given:
Period (T) = 0.3 s
Time (t) = 0.6 s
Number of cycles = t / T = 0.6 / 0.3 = 2 cycles.

(6b)
Given:
Speed (v) = 2 m/s
Period (T) = 0.3 s
Wavelength (λ) = v × T = 2 × 0.3 = 0.6m
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(7a)
(i) In optical fibers
(ii) In a prism used in periscopes or binoculars

(7b)
Resonance occurs when the frequency of external force matches the natural frequency of a system, resulting in maximum amplitude WHILE Forced vibration is when a system is made to vibrate by an external force, regardless of its natural frequency.
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(8a)
Capacitor stores energy in an electric field WHILE Inductor stores energy in a magnetic field.

(8b)
Given:
v = 3 × 10⁶ m/s
θ = 60°
F = 6.23 × 10⁻¹⁴ N
q = 1.6 × 10⁻¹⁹ C

Using the Formula,
F = qvB sinθ
B = F / (qv sinθ)
= 6.23 × 10⁻¹⁴ / (1.6 × 10⁻¹⁹ × 3 × 10⁶ × sin60°)
≈ 6.23 × 10⁻¹⁴ / (4.16 × 10⁻¹³)
≈ 0.15 T

Magnetic flux density (B) ≈ 0.15 tesla
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(9a)
A potentiometer does not draw current from the source being measured, hence gives more accurate emf readings.

(9b)
• Conductor Allows easy flow of electric current (e.g., copper).
• Insulator Resists the flow of electric current (e.g., rubber).
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(10a)
• Adhesion is the force of attraction between molecules of different substances
• Cohesion is the force of attraction between molecules of the same substance

(10b)
Due to strong cohesive force between mercury molecules and weak adhesive force between mercury and glass.

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(11a)
(i) The frequency of incident radiation (higher frequency = higher energy).

(ii) The number of electrons striking the target per unit time (more electrons = greater intensity).

(11b)
Given:
λ = 6 × 10⁻⁷ m
h = 6.6 × 10⁻³⁴ Js
c = 3.0 × 10⁸ m/s

Using the Formula,
E = hc / λ
= (6.6 × 10⁻³⁴ × 3.0 × 10⁸) / (6 × 10⁻⁷)
= 1.98 × 10⁻²⁵ / 6 × 10⁻⁷
= 3.3 × 10⁻¹⁹J
Energy of the photon ≈ 3.3 × 10⁻¹⁹ joules
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(12ai)
(PICK ANY TWO)
(i) A spinning bicycle wheel.
(ii) The blades of a ceiling fan.
(iii) The Earth rotating on its axis.
(iv) A rotating grinding stone.

(12aii)
(PICK ANY TWO)
(i) A cone resting on its base
(ii) A pendulum hanging vertically downward
(iii) A book lying flat on a table
(iv) A bottle standing upright on a flat surface

(12b)
Check the diagram below

(12c)
Given three coplanar forces with components:

| S/N | Force (N) | Horizontal (N) | Vertical (N) |
|—–|———–|—————-|————–|
| 1 | 10 | -7.660 | -6.432 |
| 2 | 12 | 6.000 | 10.392 |
| 3 | 15 | 6.339 | -13.595 |

(12ci)
Total horizontal component
= -7.660 + 6.000 + 6.339 = 4.679 N

(12cii)
Total vertical component
= -6.432 + 10.392 – 13.595 = -9.635 N

(12ciii)
Magnitude of the resultant
R = √(4.679² + (-9.635)²)
= √(21.9 + 92.83) = √114.73 ≈ 10.71N
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(13ai)
(PICK ANY TWO)
(i) It has a narrow capillary tube.
(ii) It is graduated from about 35°C to 42°C.

(13aii)
To prevent mercury from flowing back, the temperature can be read after removal.

(13b)
(PICK ANY TWO)
(i) Air pollution from burning fossil fuels.
(ii) Global warming due to CO₂ emissions.
(iii) Acid rain caused by industrial gases.
(iv) Oil spills damaging aquatic life.

(13ci)
(PICK ANY ONE)
(i) Ice is solid While steam is gas
(ii) Ice forms at 0°C While steam forms at 100°C

(13cii)
(PICK ANY ONE)
(i) Both are forms of water.
(ii) Both can change state with temperature.

(13d)
Given:
Mass = 100 g = 0.1 kg
Latent heat of steam = 2.26 × 10⁶J/kg
Specific heat capacity = 4.2 × 10³J/kg·K
Final temperature = 25°C
Initial = 100°C

Condensation of steam
Q₁ = m × L = 0.1 × 2.26 × 10⁶ = 2.26 × 10⁵J

Cooling water from 100°C to 25°C
Q₂ = m × c × ΔT = 0.1 × 4.2 × 10³ × 75 = 31,500J

Total heat lost = Q₁ + Q₂ = 2.26 × 10⁵ + 3.15 × 10⁴ = 2.575 × 10⁵J
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(14a)
Diffraction is the bending or spreading of waves around obstacles or through small openings.

(14b)
(i) Concave mirror.
(ii) Convex mirror.

APPLICATION
(i) Concave mirror is used in torch lights and headlights for focusing light.
(ii) Convex mirror is used as rear-view mirrors in vehicles to provide a wider field of view.

(14c)
See Image

(14d)
Given:
Distance of A from cliff = 16 m
Echo time = 0.1 s
Distance to and from cliff = 2 × 16 = 32 m

(i) Velocity of sound = Distance / Time = 32 / 0.1 = 320 m/s

(ii) Boy B is 5 m farther = 16 + 5 = 21 m
Total distance = 2 × 21 = 42 m
Time = 42 / 320 ≈ 0.13125 s ≈ 0.13s
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(15ai)
(CHOOSE ANY THREE)
(i) Magnetic declination
(ii) Magnetic inclination
(iii) Horizontal component of Earth’s magnetic field
(iv) Vertical component of Earth’s magnetic field
(v) Magnetic field intensity

(15aii)
(CHOOSE ANY TWO)
(i) Iron is easily magnetized
(ii) Iron loses magnetism quickly when removed from the magnetic field
(iii) Iron is cheap and readily available
(iv) Iron enhances the strength of electromagnets

(15b)
(i) Total voltage across capacitors: V = V₁ + V₂
(ii) Same charge Q on each capacitor: Q = CV
(iii) Use Q = CV to derive 1/C = 1/C₁ + 1/C₂
(iv) Effective capacitance C = (C₁ × C₂) / (C₁ + C₂)

(15c)
Given:
R = 500 Ω, L = 6 H, f = 60 Hz

(i) Reactance of the inductor:
X_L = 2πfL = 2 × 3.14 × 60 × 6 = 2260.8 Ω

(ii) Impedance:
Z = √(R² + X_L²)
= √(500² + 2260.8²)
= √(250000 + 5109574.6)
= √5359574.6 ≈ 2315Ω
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(16a)
Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration.

(16b)
Drop a ball bearing into liquids A and B using the same cylinder and stopwatch. The liquid in which the ball falls slower is more viscous.

(16c)
(CHOOSE ANY ONE)
(i) Both x-rays and gamma rays are electromagnetic waves
(ii) Both travel at the speed of light in a vacuum
(iii) Both are used in medical and industrial imaging

(16d)
Given:
f = 2.14 × 10¹⁵ Hz,
h = 6.6 × 10⁻³⁴ Js,
K.E. = 1.09 × 10⁻¹⁸ J

(i) Energy of the photon:
E = hf = 6.6 × 10⁻³⁴ × 2.14 × 10¹⁵ = 1.41 × 10⁻¹⁸ J

(ii) Work function = E – K.E
= 1.41 × 10⁻¹⁸ − 1.09 × 10⁻¹⁸ = 0.32 × 10⁻¹⁸ = 3.2 × 10⁻¹⁹ J
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(17ai)
(CHOOSE ANY ONE)
(i)Lead dioxide (PbO₂) – positive plate
(ii) Sponge lead (Pb) – negative plate

(17aii)
(CHOOSE ANY ONE)
(i) Lead dioxide (PbO₂) acts as the positive electrode where reduction occurs during discharge.
(ii) Sponge lead (Pb) serves as the negative electrode where oxidation occurs during discharge.

(17b)
A solar collector absorbs sunlight and converts it to heat energy, usually for heating water or air WHILE solar panel (photovoltaic panel) converts sunlight directly into electrical energy using solar cells.

(17c)
Repair is the action taken to fix a machine after it has broken down or failed WHILE Maintenance is the routine action taken to prevent breakdown, like cleaning, oiling, and checking for wear.

(17d)
(i) First image distance from the objective lens
Given:
f = 2cm (objective), u = 3cm
Using lens formula: 1/f = 1/v – 1/u
1/2 = 1/v – 1/3
(3 – 2)/6 = 1/v
1/6 = 1/v → v = 6cm

(ii) Distance between the lenses
Image distance from objective = 6cm
Distance from image to eyepiece = 7.5cm
Total = 6 + 7.5 = 13.5cm

(i) First image distance = 6cm
(ii) Distance between lenses = 13.5cm
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