MCQ Collection
ECAT Physics MCQs
Practice ECAT Physics questions with answers and explanations.
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
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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
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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
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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
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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
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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
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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
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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
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Correct Answer: D. 9 × 10^10 J
Explanation:
Use E=mc².
Choose an option to check your answer.
A.
An allowed discrete energy state of an electron in an atom
B.
Any continuously variable electron energy
C.
The total mass of the atom
D.
The electric charge of the nucleus
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Correct Answer: A. An allowed discrete energy state of an electron in an atom
Explanation:
Bound atomic electrons occupy quantized energy states.
Choose an option to check your answer.
A.
Atoms with different proton numbers but equal masses
B.
Atoms of the same element with different numbers of neutrons
C.
Ions with different charges only
D.
Molecules with different structures
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Correct Answer: B. Atoms of the same element with different numbers of neutrons
Explanation:
Isotopes have the same atomic number and chemical identity.
Choose an option to check your answer.
A.
Chemical burning of atoms
B.
Forced ionization by heat only
C.
Spontaneous transformation of unstable nuclei with emission of radiation
D.
Reflection of electromagnetic waves
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Correct Answer: C. Spontaneous transformation of unstable nuclei with emission of radiation
Explanation:
Radioactive decay is a nuclear process.
