MCQ Collection
Pakistan MCQs
Practice Pakistan questions with answers and explanations.
Choose an option to check your answer.
A.
2 eV
B.
5 eV
C.
3 eV
D.
10 eV
Show Answer
Correct Answer: C. 3 eV
Explanation:
The photon energy equals the difference between levels.
Choose an option to check your answer.
A.
4 V
B.
25 V
C.
500 V
D.
100 V
Show Answer
Correct Answer: D. 100 V
Explanation:
Voltage ratio equals turns ratio.
Choose an option to check your answer.
A.
200
B.
600
C.
800
D.
400
Show Answer
Correct Answer: D. 400
Explanation:
One half-life reduces the undecayed population by half.
Choose an option to check your answer.
A.
Discrete packets of energy
B.
Only continuous mechanical waves
C.
Massive charged particles
D.
Stationary electric fields
Show Answer
Correct Answer: A. Discrete packets of energy
Explanation:
A photon carries energy proportional to frequency.
Choose an option to check your answer.
A.
100
B.
50
C.
200
D.
400
Show Answer
Correct Answer: A. 100
Explanation:
After three half-lives, the remaining fraction is (1/2)^3=1/8.
Choose an option to check your answer.
A.
Production of light by heated metals only
B.
Emission of electrons from a surface when light of sufficient frequency falls on it
C.
Deflection of electrons by a magnetic field
D.
Creation of neutrons by visible light
Show Answer
Correct Answer: B. Emission of electrons from a surface when light of sufficient frequency falls on it
Explanation:
Photoelectric emission requires photon energy above the material's work function.
Choose an option to check your answer.
A.
1/2
B.
1/4
C.
1/3
D.
1/8
Show Answer
Correct Answer: B. 1/4
Explanation:
Twelve hours equals two half-lives.
Choose an option to check your answer.
A.
Energy of every electron in the atom
B.
Maximum photon energy
C.
Minimum energy needed to remove an electron from its surface
D.
Energy stored in a capacitor
Show Answer
Correct Answer: C. Minimum energy needed to remove an electron from its surface
Explanation:
The work function depends on the material and surface condition.
Choose an option to check your answer.
A.
2
B.
4
C.
3
D.
8
Show Answer
Correct Answer: C. 3
Explanation:
The sequence is 1600, 800, 400, 200.
Choose an option to check your answer.
A.
Particles can never behave like waves
B.
Only photons have momentum
C.
Mass and energy are unrelated
D.
Moving particles have an associated wavelength
Show Answer
Correct Answer: D. Moving particles have an associated wavelength
Explanation:
Matter waves link momentum with wavelength through λ=h/p.
Choose an option to check your answer.
A.
3 × 10^2 J
B.
9 × 10^4 J
C.
3 × 10^14 J
D.
9 × 10^10 J
Show Answer
Correct Answer: D. 9 × 10^10 J
Explanation:
Use E=mc².
Choose an option to check your answer.
A.
10 Ω
B.
2.1 Ω
C.
4 Ω
D.
21 Ω
Show Answer
Correct Answer: A. 10 Ω
Explanation:
Series resistances add directly.
