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CBSE Questions for Class 12 Medical Physics Atoms Quiz 14 - MCQExams.com

The ionization energy of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by electromagnetic radiation of energy 12.1 eV. How many spectral lines will be emitted by the hydrogen atoms?
  • one
  • two
  • three
  • four
Ionization potential of hydrogen is 13.6 volt. If it is excited by a photon of energy 12.1eV, then the number of lines in the emission spectrum will be:
  • 2
  • 3
  • 4
  • 5
The gyromagnetic ratio of an electron in an Hatom, according to Bohr model, is:-
  • Independent of which orbit it is in
  • Negative
  • Positive
  • Increase with the quantum number n
There are some atoms in ground energy level and rest of all in some upper energy level in a gas of identical hydrogen like atoms. The atoms jump to higher energy level by absorbing monochromatic light of photon energy 1.89 eV and this emit radiations of 3 photons energies. Find the principal quantum number of initially excited level.
  • 3
  • 4
  • 2
  • 5
The figure shows the velocity and acceleration of a point like body at the initial moment of its motion. The acceleration vector of the body remains constant. The minimum radius of curvature of trajectory of the body is (in m)
1065015_323c0645f10c4f62a45cb4dda2014c20.PNG
  • 2 m
  • 4 m
  • 8 m
  • 16 m
According to Bohr's theory of hydrogen atom, the speed of the electron, its energy and the radius of its orbit varies with the principal quantum number n, respectively as:
  • 1n,1n2,n2
  • 1n,n2,1n2
  • n2,1n2,n2
  • n,1n2,1n2
Taking the Bohr radius as a0=35pm, the radius of Li++ion in its ground state, on the basis of Bohr's model, will be about
  • 53pm
  • 27 pm
  • 18 pm
  • 13 pm
Consider Bohr's theory for hydrogen atom. The magnitude of angular momentum, orbit radius and frequency of the electron in nth energy state in a hydrogen atom are, r and f respectively. find out the value of X, if (frl) is directly proportional to nx.
  • 1
  • 0
  • 2
  • 3
Electron in a hydrogen atom is replaced by an identically charged particle muon with mass 207 times that of electron . Now the radius of K shell will be 
  • 2.56×103˚A
  • 109.7˚A
  • 1.21×103˚A
  • 22174.4˚A
An ionic atom equivalent to hydrogen atom has wavelength equal to 14 of the wavelengths of hydrogen lines. The ion will be
  • He+
  • Li++
  • Ne9+
  • Na10+
The third line of Balmer series of an ion equivalent to hydrogen atom has wavelength of 108.5nm. the ground state energy of an electron of this ion will be
  • 3.4eV
  • 13.6eV
  • 54.4eV
  • 122.4eV
If the kinetic energy of an electron in the first orbit of H atom is 13.6eV. Then the total energy of an electron in the second orbit of He+ is:
  • 13.6eV
  • 3.4eV
  • 13.6eV
  • 3.4eV
Which of the following weighs the least? 
  • 2 g atom of N (atomic wt of N =14)
  • 3×1023 atoms of C (atomic wt. of C=12)
  • 1 mole of S ( atomic weight of S = 32 )
  • 7 g silver ( atomic wt. of Ag =108)
In a hypothetical system a particle of mass m and charge 3q is moving around a very heavy particle having charge q. Assuming Bohr's model to be true to this system, the orbital velocity of mass m when it is nearest to the heavy particle is
  • 3q22ϵ0h
  • 3q24ϵ0h
  • 3q2ϵ0h
  • 3q4ϵ0h
A positronium consists of an electron and a positron revolving about their common centre of mass. Calculate the separation between the electron and positron in their first excited state:
  • 0.529 A
  • 1.058 A
  • 2.116 A
  • 4.232 A
The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 A. The wavelength of the second spectral line in the Balmer series of singly ionized helium atom is :
(in  Ao
  • 1215 
  • 1640 
  • 2430 
  • 4687 
Calculate number of electrons present in 500 cm3 volume of water.
  • 1.67×1020
  • 1.67×1026
  • 1.67×1023
  • 3.2×1026
The magnitude of angular momentum, orbit radius and frequency of revolution of electron in hydrogen atom corresponding to quantum number n are L,r and f respectivey. Then according to Bohr's theory of hydrogen atom
  • fr2L is constant for all orbits
  • frL is constant for all orbits
  • f2rL is constant for all orbits
  • frL2 is constant for all orbits
The electron in a hydrogen atom makes a transition n1n2 whose n1 and n2 are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The frequency of orbital motion of the electron in the initial state is 1/27 of that in the final state. The possible values of n1 and n2 are
  • n1=4,n2=2
  • n1=3,n2=1
  • n1=8,n2=1
  • n1=6,n2=3
The wavelength of the first member of the Balmer series in hydrogen spectrum is x ˚A. Then the wavelength (in ˚A) of the first member of Lyman series in the same spectrum is
  • 527x
  • 43x
  • 275x
  • 536x
In a hypothetical system a particle of mass m and charge -3q is moving around a very heavy particle having charge q. Assuming Bohr's model to be true to this system, The orbital velocity of mass m when it is nearest to heavy particle is 
  • 3q22ε0h
  • 4q22ε0h
  • 3q2ε0h
  • 3q4ε0h
An electron collides with a fixed hydrogen atom in its ground state. Hydrogen atom gets excited and the colliding electron loses all its kinetic energy. Consequently the hydrogen atom may emit a photon corresponding to the largest wavelength of the Balmer series. The main KE of colliding electron will be
  • 10.2eV
  • 1.9eV
  • 12.1eV
  • 13.6eV
If Rutherford would have used β-particles instead of α-particles in his Goldleaf experiment which of the following observation would definitely not have been made?
  • Get condensed or concentrated
  • Majority of β-particles passing unperfected through the foil
  • Very few α-particles getting absorbed
  • Wave nature of electron
The ratio of areas within the electron orbits for the first excited state to the ground state for hydrogen atom is
  • 16:1
  • 18:1
  • 4:1
  • 2:1
The electric potential between a proton and an electron is given by V=VInrr0, where r0 is a constant. Assuming Bohr's model to be applicable,write variation of rn with n, n being the principal quantum number.
  • rnn
  • rn1n
  • rnn2
  • rn1n2
Choose the correct statement (s) for hydrogen and deuterium atoms considering motion of reaction
  • The radius of first Bohr orbit of deuterium is less than that of hydrogen
  • The speed of electron in the first Bohr orbit of deuterium is more that that of hydrogen
  • The wave length of first Balmer line of deuterium is more than that of hydrogen
  • The angular momentum of electron in the first Bohr orbit of deuterium is more than that of hydrogen
According to Bohr's theory of the hydrogen atom, the speed vn of the electron in a stationary orbit is related to the principal quantum number n as (C is a constant).
  • vn=C/n2
  • vn=C/n
  • vn=C×n
  • vn=C×n2
Assuming Bohr's model for Li++ atom, the first excitatio energy of ground state of Li++ atom is
  • 10.2 eV
  • 91.8 eV
  • 13.6 eV
  • 3.4 eV
The energy levels of a certain atom for 1st, 2nd and 3rd levels are E, 4E13 and 2E respectively. A photon of wavelength λ is emitted for a transition 31. What will be the wavelength of emissions for transition 21:
  • λ/3
  • 4λ/3
  • 3λ/4
  • 3λ
Assuming Bohr's model for Li++ atom, the first excitation energy of ground state of Li++ atom is
  • 10.2eV
  • 91.8eV
  • 13.6eV
  • 3.4eV
In a hypothetical system a particle of mass m and charge -3 q is moving around a very heavy particle having charge q. Assuming Bohr's model to be true to this system, the orbital velocity of mass m when it is nearest to heavy particle is:
  • 3q22ε0h
  • 3q24ε0h
  • 3q2ε0h
  • 3q4ε0h
A hydrogen atoms emits green light when it changes from the n=4 energy level to n=2 level. which color of light would the atom emit when it changes from the n=5 level to n=2 level ?
  • red
  • yellow
  • green
  • violet
If the ionisation energy of a hydrogen like Bohr atom is 4 Rydberg, then the wavelengths of radiation emitted when the electron jumps from first excited state to the ground state and the radius of the first orbit of this atom are:
  • 3.04A,0.53A
  • 304A,0.265A
  • 912A,0.53A
  • 3.04A,0.265A
Find an expression for de Broglie wavelength for an electron in the nth orbit of the Bohr model of the hydrogen atom and hence find its value when the electron is in n = 4 level.
Take radius of nth orbital of Bohr's model of H-atom; rn=(53 n2) pm
  • 1.33 nm
  • 1.20 nm
  • 1.50 nm
  • None
The innermost orbit of the hydrogen atom has a diameter of 1.06Ao. What is the diameter of the tenth orbit?
  • 5.3Ao
  • 10.6Ao
  • 53Ao
  • 106Ao
An electron jumps from the 4th orbit to the 2nd orbit of hydrogen atom (R=105 Cm1). Frequency is in Hz of emitted radiation will be
  • 3 ×10516
  • 3 ×101516
  • 9 ×101516
  • 9 ×10516
In a Geiger-Marsden experiment if the distance of closest approach is d to the nucleus and an α particle of energy E then
  • dE
  • d1E
  • d2E
  • d21E
The Ha-line of hydrogen
  • has a wavelength 4860 0A
  • has a wavelength 65620A
  • has a wavelength smaller then that of the Hβ-line
  • is emitted in the transition from the second excited state of the first excited state
According to Bohr modal, magnetic field at the centre (at the nucleus) of a hydrogen atom due to the motion of electron in nth orbit is proportional to:
  • 1/n3
  • n3
  • n5
  • 1/n5
The wave number of first line in Balmer series of hydrogen spectrum is (Rydberg constant, RH=109,687cm1) nearly
  • 82,259cm1
  • 152,00cm1
  • 97,492cm1
  • 15,200cm1
Which of the following is inversely proportional to the square of principal quantum number in Bohr's atomic model?
  • Total energy of the electron in nth orbit.
  • Radius of the nth orbit.
  • Frequency of revolution in nth orbit.
  • Time period of revolution in nth orbit.
Choose the correct statements for hydrogen and deuterium atoms ( considering motion of nuclie as )
  • The radius of first Bohr orbit of deuterium is less than that of hydrogen
  • The speed of electron in the first Bohr orbit of deuterium is more than that of hydrogen.
  • The wavelength of first Balmer line of deuterium is more than that of hydrogen
  • The angular momentum of electron in the first Bohr orbit of deuterium is more than that of hydrogen.
The ratio of the radii of the electron orbits for the first excited state to the ground state for the hydrogen atom is:
  • 2 : 1
  • 4 : 1
  • 8 : 1
  • 16 : 1
The wave number of first line of Balmer series of hydrogen atom is 15200 cm1. What is the wave number of first line of Balmer series of Li2+ ion.
  • 15200 cm1
  • 136800 m1
  • 76000 cm1
  • 13680 cm1
In a Bohr atom the electron is replaced by a particle of mass 150 times the mass of the electron an the same charge, If a0 is the radius of the first Bohr orbit of the orbital atom, then that of the new atom will be 
  • 150a0
  • 150a0
  • a0150
  • a0150
The ionization potential of H-atom is 13.6V. The H-atoms in ground state are excited by monochromic radiations of photon energy 12.09 eV. Then the number of spectral lines emitted by the excited atoms will be: 
  • 1
  • 2
  • 3
  • 4
A 12.5eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of spectral line will be emitted ?
  • 1 Lyman, 2 Balmer
  • 2 Lyman, 1 Balmer
  • 1 Lyman, 1 Balmer, 1 Paschen
  • 3 Balmer
The wavelength of the first member of the Balmer series is 656.3 nm. The wavelength of the second line of the Lyman series is
  • 81.02 nm
  • 121.6 nm
  • 364.8 nm
  • 729.6 nm
The speed of sound in air is v. Both the source and observer are moving towards each other with equal speed u. The speed of wind isw from source to observer. Then, the ratio (ff0) of the apparent frequency to the actual frequency is given by
  • v+uvu
  • v+w+uv+wu
  • v+w+uvwu
  • vw+uvwu
According to Moseley's law, the ratio of the slope of graph between f and Z for kβ and kα is
  • 3227
  • 2732
  • 556
  • 365
0:0:1


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