Physics · Textbook solutions
Atoms
Every solved example, exercise, and miscellaneous question, in the order the textbook teaches them. Plus every board question asked from this chapter. · 13 questions
Worked Examples
4 q
Solved Examples
Worked · 4
- Eg 12.1In the Rutherford's nuclear model of the atom, the nucleus (radius about ) is analogous to the sun about which the electron move in orbit (radius ) like the earth orbits around the sun. If the dimensions of the solar system had the same proportions as those of the atom, would the earth be closer to or farther away from the sun than actually it is? The radius of earth's orbit is about . The radius of sun is taken as .
- Eg 12.2In a Geiger-Marsden experiment, what is the distance of closest approach to the nucleus of a -particle before it comes momentarily to rest and reverses its direction?
- Eg 12.3It is found experimentally that energy is required to separate a hydrogen atom into a proton and an electron. Compute the orbital radius and the velocity of the electron in a hydrogen atom.
- Eg 12.4According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom.
Exercises
9 q
- Ex 12.1Choose the correct alternative from the clues given at the end of the each statement: (a) The size of the atom in Thomson's model is .......... the atomic size in Rutherford's model. (much greater than/no different from/much less than.) (b) In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force. (Thomson's model/ Rutherford's model.) (c) A classical atom based on .......... is doomed to collapse. (Thomson's model/ Rutherford's model.) (d) An atom has a nearly continuous mass distribution in a .......... but has a highly non-uniform mass distribution in .......... (Thomson's model/ Rutherford's model.) (e) The positively charged part of the atom possesses most of the mass in .......... (Rutherford's model/both the models.)
- Ex 12.2Suppose you are given a chance to repeat the alpha-particle scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below .) What results do you expect?
- Ex 12.3A difference of separates two energy levels in an atom. What is the frequency of radiation emitted when the atom make a transition from the upper level to the lower level?
- Ex 12.4The ground state energy of hydrogen atom is . What are the kinetic and potential energies of the electron in this state?
- Ex 12.5A hydrogen atom initially in the ground level absorbs a photon, which excites it to the level. Determine the wavelength and frequency of photon.
- Ex 12.6(a) Using the Bohr's model calculate the speed of the electron in a hydrogen atom in the , , and levels. (b) Calculate the orbital period in each of these levels.
- Ex 12.7The radius of the innermost electron orbit of a hydrogen atom is . What are the radii of the and orbits?
- Ex 12.8A electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?
- Ex 12.9In accordance with the Bohr's model, find the quantum number that characterises the earth's revolution around the sun in an orbit of radius with orbital speed . (Mass of earth .)
What the board has asked from this chapter
Questions per paper · 26 papers · 2022 to 2026
Bars average the full papers of each year. 38 further questions come from set variants and are listed below.
2022: 2 questions per paper. 2023: 3 questions per paper. 2024: 3 questions per paper. 2025: 2.3 questions per paper. 2026: 1.8 questions per paper
2026
19 q
- 3In Bohr model of hydrogen atom, the value of potential energy of an electron in orbit varies with 'n' as
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Bohr Model of the Hydrogen Atom - 4In Bohr model of hydrogen atom, for large values of n, the distance between the consecutive orbits is proportional to
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Bohr Model of the Hydrogen Atom - 5In Bohr model of hydrogen atom, an electron makes a transition from n = 4 state to n = 1 state and a photon of frequency is emitted. The frequency of photon emitted when an electron makes a transition from n = 4 state to n = 2 state in the same model is
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Line Spectra of the Hydrogen Atom - 6The distance-of-closest-approach for an alpha particle is 'd' when it moves head-on with speed v towards a target nucleus. If the alpha particle is replaced by a proton moving with the same speed, the new distance-of-closest-approach will be
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Alpha-Particle Scattering and Rutherford's Model - 8The ratio of the potential energy to the kinetic energy of an electron in orbit of Bohr model of hydrogen atom is
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Bohr Model of the Hydrogen Atom - 8The 'distance of closest approach' of an alpha-particle is 'd' when it moves with a velocity head-on towards the target nucleus. If the velocity of alpha particle is halved, the new 'distance of closest approach' will be -
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Alpha-Particle Scattering and Rutherford's Model - 9In Bohr model of hydrogen atom, an electron is moving in an orbit, with total energy eV. Its angular momentum will be
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Bohr Model of the Hydrogen Atom - 10According to Bohr model of hydrogen atom, the time period of an electron in its orbit is proportional to
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Bohr Model of the Hydrogen Atom - 10The energy of an electron in an orbit in hydrogen atom is eV. Its angular momentum in the orbit will be :
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Bohr Model of the Hydrogen Atom - 10The ratio of the de Broglie wavelengths associated with the electron revolving in the first and third orbits in hydrogen atom is :
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de Broglie's Explanation of Bohr's Postulate - 11Paschen series in spectrum of hydrogen atom lies in :
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Line Spectra of the Hydrogen Atom - 12In Bohr model of hydrogen atom, the electron makes a transition from n = 5 to n = 1 state. As a result, a photon of wavelength is emitted in the process. The wavelength of the photon emitted when an electron makes a transition from energy level n = 5 to n = 2 will be
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Line Spectra of the Hydrogen Atom - 12The energy of an electron revolving in the orbit in Bohr model of hydrogen atom is proportional to :
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Bohr Model of the Hydrogen Atom - For question number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the options (A), (B), (C) and (D) as given below :16Reason (A) : In Bohr model of hydrogen atom, the energy levels are discrete and quantised. Reason (R) : In a hydrogen atom, the electrostatic force on the electron provides the necessary centripetal force to it to revolve around the nucleus.
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Bohr Model of the Hydrogen Atom - 20Draw the graph showing the variation of number of scattered alpha particles (N) detected with scattering angle in Geiger-Marsden experiment. Infer two conclusions from the graph.Alpha-Particle Scattering and Rutherford's Model
- 24In Bohr model of hydrogen atom, calculate : (a) the radius of the innermost electron orbit, and (b) the speed of electron in this orbit.Bohr Model of the Hydrogen Atom
- 26 (b)(i) Draw the number of scattered particles versus the scattering angle graph for scattering of alpha particles by a thin foil. Write two important conclusions that can be drawn from this plot. (ii) If Bohr's quantization postulate (angular momentum = ) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun ? Explain.Alpha-Particle Scattering and Rutherford's Model
- 26(a) State Bohr's second postulate and mention its significance. (b) Prove that, in Bohr model of hydrogen atom as principal quantum number n becomes large, the energy levels get closer and closer.Bohr Model of the Hydrogen Atom
- 28A deuterium nucleus and an alpha particle approach a target nucleus separately in head-on position. Find the ratio of their distance of closest approach to the nucleus, when both have : (a) the same velocity, and (b) the same momentum.Alpha-Particle Scattering and Rutherford's Model
2025
24 q
- 10The minimum energy required to free the electron from the ground state of the hydrogen atom is :
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Bohr Model of the Hydrogen Atom - 10Out of the four options given, in which transition will the emitted photon have the maximum wavelength ?
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Line Spectra of the Hydrogen Atom - 11The energy of an electron in a hydrogen atom in ground state is eV. Its energy in an orbit corresponding to quantum number n is eV. The value of n is
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Bohr Model of the Hydrogen Atom - For Questions 13 to 16, two statements are given – one labelled Assertion (A) and other labelled Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :14Assertion (A) : In Bohr model of hydrogen atom, the angular momentum of an electron in orbit is proportional to the square root of its orbit radius . Reason (R) : According to Bohr model, electron can jump to its nearest orbits only.
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Bohr Model of the Hydrogen Atom - Questions number 13 to 16 are Assertion (A) and Reason (R) type questions. Two statements are given — one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.15Assertion (A) : The Balmer series in hydrogen atom spectrum is formed when the electron jumps from higher energy state to the ground state. Reason (R) : In Bohr's model of hydrogen atom, the electron can jump between successive orbits only.
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Line Spectra of the Hydrogen Atom - Questions number 13 to 16 are Assertion (A) and Reason (R) type questions. Two statements are given — one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.16Assertion (A) : In Rutherford's alpha particle scattering experiment, the presence of only few alpha particles at angle of scattering led him to the discovery of nucleus. Reason (R) : The size of nucleus is approximately times the size of an atom and therefore only few alpha particles are rebounded.
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Alpha-Particle Scattering and Rutherford's Model - Note : Question numbers 13 to 16 are Assertion (A) and Reason (R) type questions. Two statements are given – one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below :16Assertion (A) : The potential energy of an electron revolving in any stationary orbit in a hydrogen atom is positive. Reason (R) : The total energy of a charged particle is always positive.
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Bohr Model of the Hydrogen Atom - 19Define the 'distance of closest approach'. An -particle of kinetic energy K is bombarded on a thin gold foil. Derive an expression for the 'distance of closest approach'.Alpha-Particle Scattering and Rutherford's Model
- 19Define the term, 'distance of closest approach'. A proton of MeV energy approaches a target nucleus Z = 79 in head-on position. Calculate its distance of closest approach.Alpha-Particle Scattering and Rutherford's Model
- 20In Bohr's model of hydrogen atom, find the percentage change in the radius of its orbit when an electron makes a transition from n = 3 state to n = 2 state.Bohr Model of the Hydrogen Atom
- 20Find the ratio of minimum to maximum wavelength of radiations emitted when electron jumps from higher energy state into ground state of hydrogen atom.Line Spectra of the Hydrogen Atom
- 20The energy of an electron in an orbit of Bohr hydrogen atom is eV. Find its angular momentum.Bohr Model of the Hydrogen Atom
- 20An electron in Bohr model of hydrogen atom makes a transition from energy level eV to eV. Calculate the change in the radius of its orbit. The radius of orbit of electron in its ground state is 0.53 Å.Bohr Model of the Hydrogen Atom
- 20Prove that, in Bohr model of hydrogen atom, the time period of revolution of an electron in orbit is proportional to .Bohr Model of the Hydrogen Atom
- 20An alpha particle and a deuterium ion are accelerated through the same potential difference. These are then directed towards a target nucleus to make head-on collision. It is observed that their distance of closest approach is the same. Justify it theoretically.Alpha-Particle Scattering and Rutherford's Model
- 25Describe briefly Geiger-Marsden scattering experiment. Depict the graph showing the variation of number of scattered particles detected with the scattering angle. How did this graph lead to the discovery of the nucleus ?Alpha-Particle Scattering and Rutherford's Model
- 27In Bohr model of hydrogen atom, an electron is revolving in second orbit. Find the value of : (i) angular momentum of electron, (ii) radius of the orbit, and (iii) kinetic energy of electron. Take radius of first orbit of hydrogen atom as .Bohr Model of the Hydrogen Atom
- 27Write the mathematical forms of three postulates of Bohr's theory of the hydrogen atom. Using them prove that, for an electron revolving in the orbit, (a) the radius of the orbit is proportional to , and (b) the total energy of the atom is proportional to .Bohr Model of the Hydrogen Atom
- 27How is the necessary force provided to an electron to keep it moving in a circular orbit according to Bohr model of hydrogen atom ? Derive an expression for the total energy of an electron moving in an orbit of radius r in hydrogen atom. Give the significance of negative sign in this expression.Bohr Model of the Hydrogen Atom
- A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum of the electron in these orbits is some integral multiple of , where h is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as m and e respectively, answer the following questions.30 (i)The expression for the speed of electron v in terms of radius of the orbit (r) and physical constant () is :
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Bohr Model of the Hydrogen Atom - A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum of the electron in these orbits is some integral multiple of , where h is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as m and e respectively, answer the following questions.30 (ii)The total energy of the atom in terms of r and physical constant K is :
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Bohr Model of the Hydrogen Atom - A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum of the electron in these orbits is some integral multiple of , where h is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as m and e respectively, answer the following questions.30 (iii)A photon of wavelength 500 nm is emitted when an electron makes a transition from one state to the other state in an atom. The change in the total energy of the electron and change in its kinetic energy in eV as per Bohr's model, respectively will be :
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Bohr Model of the Hydrogen Atom - A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum of the electron in these orbits is some integral multiple of , where h is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as m and e respectively, answer the following questions.30 (iv) (a)In Bohr's model of hydrogen atom, the frequency of revolution of electron in its orbit is proportional to :
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Bohr Model of the Hydrogen Atom - A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a proton located at the nucleus of the atom. The electrostatic force of attraction between the revolving electron and the proton provides the requisite centripetal force to keep it in the orbit. According to Bohr's model, an electron can revolve only in certain stable orbits. The angular momentum of the electron in these orbits is some integral multiple of , where h is the Planck's constant. Further, when an electron makes a transition from one orbit of higher energy to that of lower energy, a photon is emitted having energy equal to the difference between energies of the initial and final states. Assuming the mass and charge of an electron as m and e respectively, answer the following questions.30 (iv) (b)An electron makes a transition from eV state to the ground state in hydrogen atom. Its radius of orbit changes by : (radius of orbit of electron in ground state = Å)
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Bohr Model of the Hydrogen Atom
2024
22 q
- 4The radius of orbit in Bohr model of hydrogen atom varies with n as
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Bohr Model of the Hydrogen Atom - 9Energy levels A, B and C of an atom correspond to increasing values of energy i.e. . Let , and be the wavelengths of radiation corresponding to the transitions C to B, B to A and C to A, respectively. The correct relation between , and is :
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Atomic Spectra - 9The energy of an electron in the ground state of hydrogen atom is eV. The kinetic and potential energy of the electron in the first excited state will be
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Bohr Model of the Hydrogen Atom - 9A proton and an alpha particle having equal velocities approach a target nucleus. They come momentarily to rest and then reverse their directions. The ratio of the distance of closest approach of the proton to that of the alpha particle will be :
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Alpha-Particle Scattering and Rutherford's Model - 9The transition of electron that gives rise to the formation of the second spectral line of the Balmer series in the spectrum of hydrogen atom corresponds to :
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Line Spectra of the Hydrogen Atom - 10An alpha particle approaches a gold nucleus in Geiger-Marsden experiment with kinetic energy K. It momentarily stops at a distance d from the nucleus and reverses its direction. Then d is proportional to :
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Alpha-Particle Scattering and Rutherford's Model - 11An electron makes a transition from n = 2 level to n = 1 level in the Bohr model of a hydrogen atom. Its period of revolution :
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Bohr Model of the Hydrogen Atom - 12In Balmer series of hydrogen atom, as the wavelength of spectral lines decreases, they appear
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Line Spectra of the Hydrogen Atom - For Questions 13 to 16, two statements are given – one labelled Assertion (A) and other labelled Reason (R). Select the correct answer to these questions from the options as given below. (A) If both Assertion (A) and Reason (R) are true and Reason (R) is correct explanation of Assertion (A). (B) If both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A). (C) If Assertion (A) is true but Reason (R) is false. (D) If both Assertion (A) and Reason (R) are false.16Assertion (A) : An alpha particle is moving towards a gold nucleus. The impact parameter is maximum for the scattering angle of 180°. Reason (R) : The impact parameter in an alpha particle scattering experiment does not depend upon the atomic number of the target nucleus.
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Alpha-Particle Scattering and Rutherford's Model - 20In Bohr model of hydrogen atom, find the ratio of period of revolution of the electron in the orbit n = 2 to that in the orbit n = 1.Bohr Model of the Hydrogen Atom
- 20(a) Two energy levels of an electron in hydrogen atom are separated by 2.55 eV. Find the wavelength of radiation emitted when the electron makes transition from the higher energy level to the lower energy level. (b) In which series of hydrogen spectrum this line shall fall ?Line Spectra of the Hydrogen Atom
- 21A proton of energy 1.6 MeV approaches a gold nucleus (Z = 79). Find the distance of its closest approach.Alpha-Particle Scattering and Rutherford's Model
- 21The electron in hydrogen atom is revolving with the speed of m/s in an orbit of radius 0.53 Å. Calculate the initial frequency of light emitted by the electron using classical physics.Alpha-Particle Scattering and Rutherford's Model
- 21The earth revolves around the sun in an orbit of radius m with orbital speed 30 km/s. Find the quantum number that characterises its revolution using Bohr's model in this case (mass of earth kg).Bohr Model of the Hydrogen Atom
- 24Draw the graph showing variation of scattered particles detected (N) with the scattering angle in Geiger-Marsden experiment. Write two conclusions that you can draw from this graph. Obtain the expression for the distance of closest approach in this experiment.Alpha-Particle Scattering and Rutherford's Model
- 26State Bohr's second postulate for his theory of hydrogen atom. Prove that the radius of Bohr's orbit of a hydrogen atom is directly proportional to , where n is the principal quantum number.Bohr Model of the Hydrogen Atom
- 26Explain the origin of the spectral lines of hydrogen atom using Bohr's theory. Draw the energy level diagram of hydrogen atom showing its various spectral series.Line Spectra of the Hydrogen Atom
- 26State Bohr's first and second postulates. Use them to derive an expression for the radius of the orbit in a hydrogen atom.Bohr Model of the Hydrogen Atom
- 26Using Bohr's postulates, derive the expression for the radius of the orbit of an electron in a hydrogen atom. Also find the numerical value of Bohr's radius .Bohr Model of the Hydrogen Atom
- 27Write the drawbacks of Rutherford's atomic model. How did Bohr remove them ? Show that different orbits in Bohr's atom are not equally spaced.Bohr Model of the Hydrogen Atom
- 27Draw a schematic arrangement of Geiger-Marsden experiment. Briefly explain the conclusions drawn from the observations about the structure of an atom. Define 'distance of closest approach' in this case.Alpha-Particle Scattering and Rutherford's Model
- 27State the three postulates of Bohr's theory of hydrogen atom. A hydrogen atom de-excites from level n to level (n – 1). Show that, according to Bohr's theory, the frequency of radiation emitted , for large values of n, where is a constant. This result exactly agrees with that obtained from classical physics – one of the successes of Bohr's theory.Bohr Model of the Hydrogen Atom
2023
20 q
- 2Specify the transition of electron in the wavelength of the line in the Bohr model of hydrogen atom which gives rise to the spectral line of highest wavelength.
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Line Spectra of the Hydrogen Atom - 10The diagram shows four energy level of an electron in Bohr model of hydrogen atom. Identify the transition in which the emitted photon will have the highest energy.
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Bohr Model of the Hydrogen Atom - 10The radius of the orbit in Bohr model of hydrogen atom is proportional to :
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Bohr Model of the Hydrogen Atom - 11A hydrogen atom makes a transition from n = 5 to n = 1 orbit. The wavelength of photon emitted is . The wavelength of photon emitted when it makes a transition from n = 5 to n = 2 orbit is
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Line Spectra of the Hydrogen Atom - 11Hydrogen atom initially in the ground state, absorbs a photon which excites it to n = 5 level. The wavelength of the photon is :
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Line Spectra of the Hydrogen Atom - 12The ratio of maximum frequency and minimum frequency of light emitted in Balmer series of hydrogen spectrum, in Bohr’s model is :
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Line Spectra of the Hydrogen Atom - 13The potential energy of an electron in the second excited state in hydrogen atom is :
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Bohr Model of the Hydrogen Atom - 15The radius of the n orbit in Bohr model of hydrogen atom is proportional to
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Bohr Model of the Hydrogen Atom - 22The ground state energy of hydrogen atom is eV in Bohr model. An electron makes a transition from an energy level of eV to that of eV. Calculate the wavelength of the spectral line emitted.Line Spectra of the Hydrogen Atom
- 23The ground state energy of hydrogen atom is eV. What is the potential energy and kinetic energy of an electron in the third excited state ?Bohr Model of the Hydrogen Atom
- 23 (a)What is meant by ionisation energy ? Write its value for hydrogen atom.Bohr Model of the Hydrogen Atom
- 23 (b)Using Bohr’s postulates, obtain the expression for radius of stable orbit in a hydrogen atom.Bohr Model of the Hydrogen Atom
- 25Calculate the wavelength of the second line of Lyman series in a spectrum of hydrogen atom. (Take Rydberg constant, R = )Line Spectra of the Hydrogen Atom
- 28(a) Differentiate between 'impact parameter' and 'distance of closest approach' in alpha particle scattering experiment. Identify, situations when impact parameter is (i) minimum, and (ii) very large. (b) An electron cannot revolve around the nucleus in a hydrogen atom at an arbitrary distance. Explain.Alpha-Particle Scattering and Rutherford's Model
- 30 (a)(i) Differentiate between 'distance of closest approach' and 'impact parameter'. (ii) Determine the distance of closest approach when an alpha particle of kinetic energy 3.95 MeV approaches a nucleus of Z = 79, stops and reverses its directions.Alpha-Particle Scattering and Rutherford's Model
- 30 (a)Draw the energy level diagram for hydrogen atom. Mark the transitions corresponding to the series lying in the ultraviolet region, visible region and infrared region.Line Spectra of the Hydrogen Atom
- 30 (a)(i) Write the limitations of Rutherford's model of atom. (ii) The wavelength of the second line of the Balmer series in the hydrogen spectrum is 4861 Å. Calculate the wavelength of the first line of the same series.Line Spectra of the Hydrogen Atom
- 30 (b)(i) Draw a graph to show the variation of the number of scattered particles detected (N) in Geiger-Marsden experiment as a function of scattering angle . (ii) Discuss briefly two conclusions that can be drawn from this graph and how they lead to the discovery of nucleus in an atom.Alpha-Particle Scattering and Rutherford's Model
- 30Briefly explain Geiger-Marsden experiment. Show the variation of the number of particles scattered (N) with scattering angle in this experiment. What is the main conclusion that can be inferred from this plot ?Alpha-Particle Scattering and Rutherford's Model
- 30 (b)(i) State three postulates of Bohr's theory of hydrogen atom. (ii) Find the angular momentum of an electron revolving in the second orbit in Bohr's hydrogen atom.Bohr Model of the Hydrogen Atom
2022
16 q
- 2 (a)(i) Define the terms : 'impact parameter' and 'distance of closest approach' for an -particle in Geiger-Marsden scattering experiment. (ii) What will be the value of the impact parameter for scattering angle (I) and (II) ?Alpha-Particle Scattering and Rutherford's Model
- 2 (a)Name the spectral series for a hydrogen atom which lies in the visible region. Find the ratio of the maximum to the minimum wavelengths of this series.Line Spectra of the Hydrogen Atom
- 2 (a)What results do you expect if -particle scattering experiment is repeated using a thin sheet of hydrogen in place of a gold foil ? Explain. (Hydrogen is a solid at temperature below 14K)Alpha-Particle Scattering and Rutherford's Model
- 2 (a)Draw the graph showing the variation of the number (N) of scattered alpha particles with scattering angle in Geiger – Marsden experiment. Infer two conclusions from the graph.Alpha-Particle Scattering and Rutherford's Model
- 4Define the term – Distance of closest approach. How will it be affected, for an - particle, if kinetic energy of the particle is doubled ?Alpha-Particle Scattering and Rutherford's Model
- 4State Bohr's postulate to explain stable orbits in a hydrogen atom. Prove that the speed with which the electron revolves in orbit is proportional to .Bohr Model of the Hydrogen Atom
- 4Draw a graph showing the variation of number of particles scattered (N) with the scattering angle in Geiger-Marsden experiment. Why only a small fraction of the particles are scattered at ? Mention two limitations of Rutherford nuclear model of an atom.Alpha-Particle Scattering and Rutherford's Model
- 6A narrow beam of protons, each having 4.1 MeV energy is approaching a sheet of lead . Calculate : (i) the speed of a proton in the beam, and (ii) the distance of its closest approachAlpha-Particle Scattering and Rutherford's Model
- 6(a) In Geiger-Marsden experiment, calculate the distance of closest approach for an alpha particle with energy J. Consider that the particle approaches gold nucleus in head-on position. (b) If the above experiment is repeated with a proton of the same energy, then what will be the value of the distance of closest approach ?Alpha-Particle Scattering and Rutherford's Model
- 5An electron in a hydrogen atom makes transitions from orbits of higher energies to orbits of lower energies. (i) When will such transitions result in (a) Lyman (b) Balmer series ? (ii) Find the ratio of the longest wavelength in Lyman series to the shortest wavelength in Balmer series.Line Spectra of the Hydrogen Atom
- 8The energy of a hydrogen atom in the first excited state is eV. Find : (a) the radius of this orbit. (Take Bohr radius = Å) (b) the angular momentum of the electron in the orbit. (c) the kinetic and potential energy of the electron in the orbit.Bohr Model of the Hydrogen Atom
- 9(a) Sketch the energy level diagram for hydrogen atom. (b) Find the ratio of the longest and the shortest wavelength in Lyman series in hydrogen atom.Line Spectra of the Hydrogen Atom
- 9(a) State Bohr's quantization condition for defining stationary orbits. (b) Use the energy level diagram shown below to obtain the relation between three wavelengths , and emitted due to the transition of electron from the energy states C and B.Bohr Model of the Hydrogen Atom
- 9(a) Use Bohr's postulate to prove that the radius of orbit in a hydrogen atom is proportional to . (b) How will the energy of a hydrogen atom change if increases from 1 to ?Bohr Model of the Hydrogen Atom
- 11(a) The energy of hydrogen atom in an orbit is eV. What are kinetic and potential energies of the electron in this orbit ? (b) The electron in a hydrogen atom is typically found at a distance of about m from the nucleus which has a diameter of about m. Assuming the hydrogen atom to be a sphere of radius m, what fraction of its volume is occupied by the nucleus ?Bohr Model of the Hydrogen Atom
- 11An electron is in the third excited state in a hydrogen atom. It undergoes transitions to the lower energy states. (a) What is the maximum number of spectral lines that can be emitted ? (b) Calculate the minimum wavelength of the spectral lines emitted.Line Spectra of the Hydrogen Atom
The 10 board questions to practise first
The questions the board asked again come first, most asked first. Each one says how often and when.
Question 1
Asked 3 times: 2022, 2023, 2026
20Draw the graph showing the variation of number of scattered alpha particles (N) detected with scattering angle in Geiger-Marsden experiment. Infer two conclusions from the graph.Question 2
Asked 3 times: 2022, 2023, 2024
26State Bohr's first and second postulates. Use them to derive an expression for the radius of the orbit in a hydrogen atom.Question 3
Asked 2 times: 2024, 2026
6The distance-of-closest-approach for an alpha particle is 'd' when it moves head-on with speed v towards a target nucleus. If the alpha particle is replaced by a proton moving with the same speed, the new distance-of-closest-approach will beTap an option to check your answer.
Question 4
Asked 2 times: 2025, 2026
10The energy of an electron in an orbit in hydrogen atom is eV. Its angular momentum in the orbit will be :Tap an option to check your answer.
Question 5
Asked 2 times: 2023, 2026
12In Bohr model of hydrogen atom, the electron makes a transition from n = 5 to n = 1 state. As a result, a photon of wavelength is emitted in the process. The wavelength of the photon emitted when an electron makes a transition from energy level n = 5 to n = 2 will beTap an option to check your answer.
Question 6
Asked 2 times: 2023, 2025
25Describe briefly Geiger-Marsden scattering experiment. Depict the graph showing the variation of number of scattered particles detected with the scattering angle. How did this graph lead to the discovery of the nucleus ?Question 7
Asked 2 times: 2024*, 2025 (* = numbers or wording changed that year)
19Define the term, 'distance of closest approach'. A proton of MeV energy approaches a target nucleus Z = 79 in head-on position. Calculate its distance of closest approach.Question 8
Asked 2 times: 2022*, 2025 (* = numbers or wording changed that year)
27In Bohr model of hydrogen atom, an electron is revolving in second orbit. Find the value of : (i) angular momentum of electron, (ii) radius of the orbit, and (iii) kinetic energy of electron. Take radius of first orbit of hydrogen atom as .Question 9
Asked 2 times: 2023, 2025
10The minimum energy required to free the electron from the ground state of the hydrogen atom is :Tap an option to check your answer.
Question 10
Asked 2 times: 2022, 2025
20Find the ratio of minimum to maximum wavelength of radiations emitted when electron jumps from higher energy state into ground state of hydrogen atom.