JEE Physics Atoms MCQs Set A

Question. According to classical theory, Rutherford atom was
(a) Electrostatically stable
(b) Electrodynamically unstable
(c) Semi stable
(d) Stable

Answer: A

Question. When a hydrogen atom is raised from the ground state to third state
(a) Potential energy increases and kinetic energy decreases
(b) Both kinetic energy and potential energy decrease
(c) Both kinetic energy and potential energy increase
(d) Potential energy decreases and kinetic energy increases

Answer: A

Question. The ground state energy of H - atom is –13.6 eV. The energy needed to ionise H - atom from its second excited state is
(a) 1.51 eV
(b) 3.4 eV
(c) 13.6 eV
(d) 12.1 eV

Answer: A

Question. If element with principal quantum number n > 4 were not allowed in nature, then the number of possible elements would be
(a) 60
(b) 32
(c) 4
(d) 64

Answer: A

Question. Of the various series of the hydrogen spectrum, the one which lies completely in the ultraviolet region is
(a) Lyman series
(b) Balmer series
(c) Paschen series
(d) Brackett series

Answer: A

Question. As the n (number of orbit) increases, the difference of energy between the consecutive energy levels
(a) Decreases
(b) Remains the same
(c) Increases
(d) Sometimes increases and sometimes decreases

Answer: A

Question. The magnetic field induction produced at the centre of orbit due to an electron revolving in n^th orbit of hydrogen atom is proportional to
(a) n^–5
(b) n^–3
(c) n⁵
(d) n³

Answer: A

Question. The speed of an electron in the orbit of hydrogen atom in the ground state is
(a) c/137
(b) c/2
(c) c/10
(d) c

Answer: A

Question. If the radius of the first orbit of hydrogen atom is 5.29 × 10^–11 m, the radius of the second orbit will be
(a) 21.16 × 10^–11 metre
(b) 15.87 × 10^–11 metre
(c) 10.58 × 10^–11 metre
(d) 2.64 × 10^–11 metre

Answer: A

Question. In Bohr’s model of the hydrogen atom, the ratio between the period of revolution of an electron in the orbit of n = 1 to the period of revolution of the electron in the orbit n = 2 is
(a) 1 : 8
(b) 1 : 4
(c) 2 : 1
(d) 1 : 2

Answer: A

Question. How many times does the electron go round the first Bohr orbit in a second?
(a) 6.57 × 10¹⁵
(b) 6.57 × 10¹³
(c) 6.57 × 10¹⁰
(d) 6.57 × 10⁵

Answer: A

Question. The ratio of the energies of the hydrogen atom in its first excited state to second excited state is
(a) 9/4
(b) 4
(c) 4/9
(d) 1/4

Answer: A

Question. Which of the following transitions in a hydrogen atom emit photons of lowest frequency?
(a) n = 4 to n = 3
(b) n = 3 to n = 1
(c) n = 4 to n = 2
(d) n = 2 to n = 1

Answer: A

Question. The energy of hydrogen-atom in its ground state is –13.6 eV. The energy of the level corresponding to n = 5 is
(a) –0.544 eV
(b) –5.40 eV
(c) –0.85 eV
(d) –2.72 eV

Answer: A

Question. The total energy of an electron in the hydrogen atom in the ground state is –13.6 eV. The kinetic energy of this electron is
(a) 13.6 eV
(b) 0
(c) –13.6 eV
(d) 6.8 eV

Answer: A

Question. Using Bohr’s formula for energy quantization, the ionisation potential of the ground state of Li⁺⁺ atoms is
(a) 122 V
(b) 13.6 V
(c) 3.4 V
(d) 10.2 V

Answer: A

Question. Which series of hydrogen atom lie in infra red region?
(a) Brackett, Paschen and Pfund
(b) Lyman
(c) Balmer
(d) All of these

Answer: A

Question. Which state of triply ionised beryllium (Be3⁺) has the same orbital radius as that of the ground state of hydrogen?
(a) 2
(b) 3
(c) 4
(d) 1

Answer: A

Question. X-rays incident on a material
(a) All of these
(b) Will transfer energy to it
(c) Will exert a force on it
(d) May cause emission of electrons

Answer: A

Question. In He-Ne laser, metastable state exists in
(a) Ne
(b) He
(c) Neither He nor Ne
(d) Both

Answer: A

Question. If the emitted radiation falls in the microwave region, the device is termed as
(a) MASER
(b) LASER
(c) Both
(d) None of these

Answer: A

Question. Laser is/are
(a) All of these
(b) Highly monochromatic
(c) Highly coherent
(d) Highly directional

Answer: A

Question. If the potential difference V applied to the coolidge tube is doubled, then the cut off wavelength
(a) Is halved
(b) Is quadrupled
(c) Is doubled
(d) Remains unchanged

Answer: A

Question. Penetrating power of X-rays increases with increase in
(a) Accelerating potential
(b) Mass number of the target material
(c) Wavelength
(d) Filament current

Answer: A

Question. An X-ray tube has a short wavelength end at 0.45Å. The voltage of tube is
(a) 27500 V
(b) 60600 V
(c) 9600 V
(d) 450000 V

Answer: A

Question. X-rays of a particular wavelength are used to irradiate sodium and copper surfaces in two separate experiments and stopping potentials are determined. The stopping potentials are
(a) Greater for sodium
(b) Greater for copper
(c) Infinite in both cases
(d) Equal in both cases

Answer: A

Question. A hydrogen atom is in ground state. In order to get six lines in its emission spectrum, wavelength of incident radiation should be
(a) 970 Å
(b) 1025 Å
(c) 825 Å
(d) 800 Å

Answer: A

Question. The X-ray beam coming from the X-rays tube will be
(a) Having all wavelengths greater than a certain minimum wavelength
(b) Dichromatic
(c) Monochromatic
(d) Having all wavelengths between a minimum and maximum wavelengths

Answer: A

Question. If the energy in the first excited state in hydrogen atom is 23.8 eV then the potential energy of a hydrogen atom in the ground state can be assumed to be
(a) Zero
(b) – 13.6 eV
(c) 23.3 eV
(d) 10 eV

Answer: A

Question. The maximum wavelength that a sample of hydrogen atoms can absorb is
(a) 1216 Å
(b) 912 Å
(c) Infinite
(d) 1028 Å

Answer: A

Question. The lines in Balmer series have their wavelengths lying between
(a) 3647 Å to 6563 Å
(b) Zero to infinity
(c) 642 Å to 3000 Å
(d) 1266 Å to 3647 Å

Answer: A

Question. If radius of first orbit of hydrogen atom is 5.29 × 10^–11 m, the radius of fourth orbit will be
(a) 8.46 Å
(b) 10.23 Å
(c) 9.22 Å
(d) 9.48 Å

Answer: A

Question. Ground state energy of H-atom is –13.6 eV. The energy needed to ionise H-atom from its second excited state is
(a) 1.51 eV
(b) 3.4 eV
(c) 13.6 eV
(d) 12.1 eV

Answer: A