Please refer to Chapter 12 Atoms MCQ Class 12 Physics with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Physics. Students should refer to MCQ Questions for Class 12 Physics with Answers to score more marks in Grade 12 Physics exams. Students should read the chapter Atoms and then attempt the following objective questions.

MCQ Questions Class 12 Physics Chapter 12 Atoms

The Atoms MCQ Class 12 Physics provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. At the time of total solar eclipse, the spectrum of solar radiation would be   
(a) a large number of dark Fraunhoffer lines
(b) a small number of dark Fraunhofer lines.
(c) All Fraunhofer lines changed into brilliant colours.
(d) None of these.

Question. If an electron jumps from Ist orbit to 4th Orbit then it will         
(a) not lose energy.
(b) absorb energy.
(c) release energy.
(d) increases and decreases periodically

Question. Consider the spectral line resulting from the transition n = 2 → n = 1 in the atoms and ions given below. The shortest wavelength is produced by
(a) hydrogen atom
(b) deuterium atom
(c) singly ionized Helium
(d) doubly ionised Lithium

Question. A hydrogen atom emits a photon corresponding to an electron transition from n = 5 to n = 1. The recoil speed of hydrogen atom is almost
(a) 10^–4 ms^–1
(b) 2 × 10^–2 ms^–1
(c) 4 ms^–1
(d) 8 × 102 ms^–1

Question. To explain fine structure of 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.

Question. When an electron jumps from the fourth orbit to the second orbit, one gets the
(a) second line of Paschen series
(b) second line of Balmer series
(c) first line of Pfund series
(d) second line of Lyman series

Question. Balmer series lies in which spectrum?         
(a) visible
(b) ultraviolet
(c) infrared
(d) partially visible, partially infrared

Question. What element has k_a line of wavelength 1.785 Å? R = 109737 cm^-1.
(a) Platinum
(b) Zinc
(c) Iron
(d) Cobalt

Question. If the ka radiation of Mo (Z = 42) has a wavelength of 0.71Å. Calculate the wavelength of the corresponding radiation of Cu (Z = 29).
(a) 1.52Å
(b) 2.52Å
(c) 0.52Å
(d) 4.52Å

Question. With increasing quantum number, the energy difference between adjacent level
(a) increases
(b) decreases
(c) same
(d) increase and then decreases

Question. According to the Rutherford’s atomic model, the electrons inside the atom are
(a) stationary
(b) not stationary
(c) centralized
(d) None of these

Question. Which of the following series in the spectrum of hydrogen atom lies in the visible region of the electromagnetic spectrum?         
(a) Paschen series
(b) Balmer series
(c) Lyman series
(d) Brackett series

Question. When hydrogen atom is in its first excited level, it’s radius is           
(a) four times, it ground state radius
(b) twice times, it ground state radius
(c) same times, it ground state radius
(d) half times, it ground state radius.

Question. The ratio of areas between the electron orbits for the first excited state to the ground state for the hydrogen atom is
(a) 2 : 1
(b) 4 : 1
(c) 8 : 1
(d) 16 : 1

Question. The potential energy associated with an electron in the orbit
(a) increases with the increases in radii of the orbit
(b) decreases with the increase in the radii of the orbit
(c) remains the same with the change in the radii of the orbit
(d) None of these

Question. The significant result deduced from the Rutherford’s scattering experiment is that           
(a) whole of the positive charge is concentrated at the centre of atom
(b) there are neutrons inside the nucleus
(c) α-particles are helium nuclei
(d) electrons are embedded in the atom

Question. As one considers orbits with higher values of n in a hydrogen atom, the electric potential energy of the atom       
(a) decreases
(b) increases
(c) remains the same
(d) does not increase

Question. Hydrogen atom excites energy level from fundamental state to n = 3. Number of spectral lines according to Bohr, is           
(a) 4
(b) 3
(c) 1
(d) 2

Question. Which of the following did Bohr use to explain his theory?             
(a) Conservation of linear momentum
(b) The quantization of angular momentum
(c) Conservation of quantum frequency
(d) Conservation of mass

Question. Rutherford’s a-particle experiment showed that the atoms have
(a) Proton
(b) Nucleus
(c) Neutron
(d) Electrons

Question. Electrons in the atom are held to the nucleus by
(a) coulomb’s force
(b) nuclear force
(c) vander waal’s force
(d) gravitational force

Question. According to Planck’s quantum theory any electromagnetic radiation is           
(a) continuously emitted
(b) continuously absorbed
(c) emitted or absorbed in discrete units
(d) None of these

Question. A set of atoms in an excited state decays.       
(a) in general to any of the states with lower energy.
(b) into a lower state only when excited by an external electric field.
(c) all together simultaneously into a lower state.
(d) to emit photons only when they collide

Question. Of the various series of the hydrogen spectrum, which of the following lies wholly in the ultraviolet region?         
(a) Balmer Series
(b) Paschen Series
(c) Brackett series
(d) Lyman Series

Question. As the quantum number increases, the difference of energy between consecutive energy levels
(a) remain the same
(b) increases 
(c) decreases
(d) sometimes increases and sometimes decreases.

Question. The electrons of Rutherford’s model would be expected to lose energy because, they             
(a) move randomly
(b) jump on nucleus
(c) radiate electromagnetic waves
(d) escape from the atom

Question. The ratio between Bohr radii is
(a) 1 : 2 : 3
(b) 2 : 4 : 6
(c) 1 : 4 : 9
(d) 1 : 3 : 5

Question. According to the Rutherford’s atomic model, the electrons inside the atom are
(a) stationary
(b) not stationary
(c) centralized
(d) None of these

Question. The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom is         
(a) 1 : 1
(b) 1 : -1
(c) 2 : -1
(d) 1 : -2

Question. According to Bohr’s theory of H atom, an electron can revolve around a proton indefinitely, if its path is   
(a) a perfect circle of any radius
(b) a circle of an allowed radius
(c) a circle of constantly decreasing radius
(d) an ellipse with fixed focus

Question. Isobars have the same:           
(a) A
(b) Z
(c) N
(d) All the above

Question. Which of the following regions does X-ray lie between?         
(a) visible and ultraviolet regions
(b) short radio waves and long radio waves
(c) short radio waves and visible region
(d) gamma rays and ultraviolet region

Question. If e is electronic charge, the equivalent current for an electron revolving with a frequency n in the ground state of hydrogen atom is
(a) 2πne
(b) e/πn
(c) e/2πn
(d) en

Question. For the azimuthal quantum number l = 3, the total number of different possible values of the magnetic azimuthal quantum number m₁, is
(a) 3
(b) 4
(c) 5
(d) 7

Question. The principle of LASER action involves
(a) amplification of particular frequency emitted by the system
(b) population inversion
(c) stimulated emissin
(d) All of the above.

Question. For the ground state, the electron in the H-atom has an angular momentum = h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,
(a) because Bohr model gives incorrect values of angular momentum.
(b) because only one of these would have a minimum energy.
(c) angular momentum must be in the direction of spin of electron.
(d) because electrons go around only in horizontal orbits.

Question. In Millikan’s oil drop experiment, an oil drop is observed to move vertically upward. The upward motion of the drop is due to
(a) gravity
(b) viscosity
(c) buoyancy
(d) electric field

Question. Balmer series lies in which spectrum?           
(a) visible
(b) ultraviolet
(c) infrared
(d) partially visible, partially infrared

Question. If the electron in the hydrogen atom jumps from third orbit to second orbit, the wavelength of the emitted radiation is ?         
(a) 5R/36
(b) 36/5R
(c) R/6
(d) 5/R

Question. How many numbers of spectral lines are observed when hydrogen atoms are excited from ground state to the state of principal quantum number 4?       
(a) 2
(b) 3
(c) 5
(d) 6

Question. An atom stays in an excited state for about:             
(a) 10 micro seconds
(b) 10 milli seconds
(c) 10 nano seconds
(d) 10 seconds

Question. The transition of electron from n = 4, 5, 6, ………. to n = 3 corresponds to         
(a) Lyman series
(b) Balmer series
(c) Paschen series
(d) Brackettseries

Question. If the wave length of first line of the Balmer series of hydrogen atom is 656.1 nm, the wave length of second line of this series would be             
(a) 218.7 nm
(b) 328.0 nm
(c) 486.0 nm
(d) 640.0 nm

Question. A spectral line is emitted when an electron         
(a) jumps from lover orbit to higher orbit.
(b) jumps from higher orbit to lower orbit.
(c) rotates in a circular orbit.
(d) rotates in an elliptical orbit.

Question. The concept of electron spin was introduced by:     
(a) Becquerel
(b) Goudsmit
(c) Millikan
(d) Uhlenbeek and Goudsmit

Question. What is the valence electron in alkali metal?         
(a) f-electron
(b) p-electron
(c) s-electron
(d) d-electron

Question. Number of nodal planes for f-orbital are           
(a) 3
(b) 2
(c) 1
(d) 0

Question. Given that in H–atom, the transition energy for n=1 to n = 2 is 10.2 eV, the energy for the same transition in Be³⁺ is         
(a) 20.4 eV
(b) 30.6 eV
(c) 40.8 eV
(d) None of these

Question. Hydrogen atoms are excited from ground state to the state of principal quantum number 4. Then, what will be the number of spectral lines observed?     
(a) 3
(b) 6
(c) 5
(d) 2

Question. The Bohr model of atoms                     
(a) assumes that the angular momentum of elec-trons is quantized.
(b) uses Einstein’s photoelectric equation.
(c) predicts continuous emission spectra for at-oms.
(d) predicts the same emission spectra for all types of atoms.

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