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NCERT Solutions for class 12 Physics | Chapter 12 - Atoms

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Free download in PDF Class 12 Physics Chapter 12 Atoms Multiple Choice Questions and Answers for Board, JEE, NEET, AIIMS, JIPMER, IIT-JEE, AIEE and other competitive exams. MCQ Questions for Class 12 Physics with Answers were prepared based on the latest exam pattern. These short solved questions or quizzes are provided by Gkseries. These will help the students for preparation of their examination./p>

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(1) 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.
Answer: assumes that the angular momentum of elec-trons is quantized.
(2) The first spectral series was discovered by
[A] Balmer
[B] Lyman
[C] Paschen
[D] Pfund
Answer: Balmer

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(3) In the Geiger-Marsden scattering experiment the number of scattered particles detected are maximum and minimum at the scattering angles respectively at
[A] 0° and 180°
[B] 180° and 0°
[C] 90° and 180°
[D] 45° and 90°
Answer: 0° and 180°
(4) Which of the following spectral series falls within the visible range of electromagnetic radiation?
[A] Lyman series
[B] Balmer series
[C] Paschen seriee
[D] Pfund series
Answer: Balmer series
(5) In Geiger-Marsden scattering experiment, the trajectory traced by an a-particle depends on
[A] number of collision
[B] number of scattered a-particles
[C] impact parameter
[D] none of these
Answer: impact parameter
(6) Which of the following postulates of the Bohr model led to the quantization of energy of the hydrogen atom?
[A] The electron goes around the nucleus in circular orbits.
[B] The angular momentum of the electron can only be an integral multiple of h/2π.
[C] The magnitude of the linear momentum of the electron is quantized.
[D] Quantization of energy is itself a postulate of the Bohr model.
Answer: The angular momentum of the electron can only be an integral multiple of h/2π.
(7) If the radius of inner most electronic orbit of a hydrogen atom is 5.3 * 10~n m, then the radii of n = 2 orbits is
[A] 1.12 Å
[B] 2.12 Å
[C] 3.22 Å
[D] 4.54 Å
Answer: 2.12 Å
(8) In the Geiger-Marsden scattering experiment, is case of head-on collision the impact parameter should be
[A] maximum
[B] minimum
[C] infinite
[D] zero
Answer: maximum
(9) The first model of atom in 1898 was proposed by
[A] Ernst Rutherford
[B] Albert Einstein
[C] J.J. Thomson
[D] Niels Bohr
Answer: J.J. Thomson
(10) The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

[A] I
[B] II
[C] III
[D] IV
Answer: III
(11) The total energy that will be released if a nucleus is built from its constituents is called the:
[A] binding energy of the nucleus
[B] binding energy of the solid
[C] binding energy of the atom
[D] None of these
Answer: binding energy of the nucleus
(12) Natural radioactivity was discovered by:
[A] Joliot
[B] Becquerel
[C] Pauli
[D] None of these
Answer: Becquerel
(13) The energy equivalent to mass defect is called :
[A] binding energy
[B] internal energy
[C] external energy
[D] enthalpy
Answer: binding energy
(14) P-decay produces:
[A] isobars
[B] isotopes
[C] isotones
[D] All the above
Answer: isobars
(15) Transmutation of nuclei was discovered by:
[A] Rutherford
[B] Becquerel
[C] Pauli
[D] None of these
Answer: Rutherford
(16) For ionization of excited Hydrogen atom, the, required energy is:
[A] a little less than 13.6
[B] equal to 13.6
[C] more than 13.6
[D] 3.4 or less
Answer: 3.4 or less
(17) The concept of electron spin was introduced by:
[A] Becquerel
[B] Goudsmit
[C] Millikan
[D] Uhlenbeek and Goudsmit
Answer: Uhlenbeek and Goudsmit
(18) The mass of a neutron is:
[A] 1.00866 u
[B] 1.0866 u
[C] 1.866 u
[D] 0.1866 u
Answer: 1.00866 u
(19) The energy equivalent to one atomic mass unit is :
[A] 1.6 × 10-19 J
[B] 6.02 × 1023 J
[C] 9.31 MeV
[D] 931 MeV
Answer: 931 MeV
(20) Half-life of a substance depends on:
[A] pressure
[B] temperature
[C] density
[D] None of these
Answer: None of these

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