Get the latest Class 12 Physics MCQs for Chapter 12, complete with answers. These MCQ questions are designed according to the latest exam pattern, helping students enhance their critical thinking skills and achieve high scores in board exams.
Atoms Class 12 MCQ Questions with Answers
Check the multiple-choice questions for the 12th Class Physics chapter on Atoms. Each question offers four options, with only one correct answer. Students should select the correct option and then verify their answers provided.
Q. What did Rutherford’s alpha particle experiment prove?
a) Electrons
b) Protons
c) Neutrons
d) Nucleus
Answer: d
Q. Why was Rutherford’s atomic model unstable?
a) Electrons do not remain in orbit
b) Nuclei will break down
c) The nucleus repels electrons
d) Orbiting electrons radiate energy
Answer: a
Q. The Balmer series lies in which spectrum?
a) Ultraviolet
b) Visible
c) Infrared
d) Partially Visible
Answer: b
Q. According to classical theory, the path of the electrons is:
a) Circular
b) Parabolic
c) Spiral
d) Straight line
Answer: c
Also Read: Electric Charges and Fields
Q. Electrons in the atom are held to the nucleus by:
a) Nuclear Force
b) Coulomb’s Force
c) Gravitational Force
d) Van Der Waal’s Force
Answer: b
Q. The electrons in Rutherford’s model would be expected to lose energy because:
a) They jump on the nucleus
b) They move randomly
c) They radiate electromagnetic waves
d) They escape from the atom
Answer: c
Q. Who discovered the first spectral series?
a) Lyman
b) Balmer
c) Paschen
d) Pfund
Answer: b
Q. Which concept did Bohr use to explain his theory?
a) Quantization of angular momentum
b) Electron clouds
c) Quantum numbers
d) Proton-electron attraction
Answer: a
Q. In Rutherford’s scattering experiment, 232 counts per minute are observed at an angle of 60°. The number of counts/min. at an angle of 120° will be:
a) 232
b) 116
c) 26
d) 52
Answer: c
Q. In an atom, the two electrons move round the nucleus in circular orbits of radii R and 4R. The ratio of the times taken by them to complete one revolution is:
a) 1/8
b) 1/4
c) 4
d) 8
Answer: a
Also Read: Current Electricity
Q. The ratio of the energies of the hydrogen atom in its first to second excited state is:
a) 1/4
b) 4/9
c) 9/4
d) 4
Answer: c
Q. In Bohr’s model of the hydrogen atom, the ratio between the period of revolution of an electron in the orbit n = 1 to the period of revolution of electron in the orbit n = 2 is:
a) 1/2
b) 1/4
c) 1/8
d) 2
Answer: c
Q. According to Bohr’s theory, the radius of electron in an orbit described by the principal quantum number n and the atomic number Z is proportional to:
a) Z²n²
b) Z²/n²
c) Z²/n
d) n²/Z
Answer: d
Q. The electron in hydrogen atom jumps from the 3rd orbit to second orbit. The wavelength X of the emitted radiations is:
a) 36/5R
b) 5/36R
c) 5/R
d) R/6
Answer: a
Q. To explain the fine structure of the spectrum of hydrogen atom, we must consider:
a) A finite size of nucleus
b) The presence of neutrons in the nucleus
c) Spin angular momentum
d) Orbital angular momentum
Answer: b
Q. The ratio of the energy of the electron in the first orbit to that in the second orbit is:
a) 1/4
b) 1/2R
c) 2
d) 4
Answer: d
Read More: Class 12 Physics Communication System MCQs
Q. When an electron jumps from some outer orbit to the innermost orbit in the hydrogen atom, the spectral line belongs to:
a) Lyman series
b) Balmer series
c) Paschen series
d) Pfund series
Answer: a
Q. How does the energy difference between two consecutive energy levels vary as the quantum number n increases?
a) Does not change
b) Decreases
c) Increases
d) May increase or decrease
Answer: b
Q. According to classical theory, Rutherford’s atom is:
a) Stable
b) Unstable
c) Metastable
d) Semistable
Answer: b
Q. For an electron orbit to be non-radiating, it should be:
a) Such that the angular momentum should be an integral multiple of h
b) Circular in nature
c) Elliptical in nature
d) None of these
Answer: a
Q. Which type of radiation is not emitted by the electronic structure of atoms?
a) X-rays
b) Visible light
c) Gamma rays
d) Ultraviolet light
Answer: c
Q. If the electron in hydrogen atoms is excited to n = 5 state, the number of different frequencies of radiation which may be emitted is:
a) 4
b) 10
c) 8
d) 5
Answer: b
Q. The ratio of the angular momentum of an electron in the first orbit to that in the second orbit is:
a) 1/2
b) 1/4
c) 4
d) 2
Answer: a
Q. The principle that a quantum orbital cannot be occupied by more than two electrons was given by:
a) Pauli
b) Millikan
c) Hund
d) None of these
Answer: a
Q. The total energy that will be released if a nucleus is built from its constituents is called:
a) Binding energy of the nucleus
b) Binding energy of the solid
c) Binding energy of the atom
d) None of these
Answer: a
Q. The spectral lines in the Brackett series arise due to the transition of electron in hydrogen atom from higher orbits to the orbit with:
a) n = 1
b) n = 2
c) n = 3
d) n = 4
Answer: d
Q. Artificial radioactivity was discovered by:
a) Joliot
b) Becquerel
c) Pauli
d) None of these
Answer: a
Q. The transition from the state n = 5 to n = 1 in a hydrogen atom results in UV radiation. Infrared radiation will be obtained in the transition:
a) 2 → 1
b) 3 → 2
c) 4 → 3
d) 6 → 2
Answer: c
Q. Natural radioactivity was discovered by:
a) Joliot
b) Becquerel
c) Pauli
d) None of these
Answer: b
Q. The energy equivalent to mass defect is called:
a) Binding energy
b) Internal energy
c) External energy
d) Enthalpy
Answer: a
