Free NEET Chemistry multiple-choice questions on Bohr's Model of Hydrogen. Attempt each question and reveal the answer with a full explanation.
According to the Bohr model, the angular momentum of an electron in the 4 th orbit of a hydrogen atom is: 2h h 4h 3h 2 The number of spectral lines obtained in the spectrum of a hydrogen-like sample when electrons transition from the n=4 level to the ground state is: 6 4 3 10 The ratio of the energy of a photon of wavelength 3000 Å to that of 6000 Å is: 2 1/2 4 1 For which of the following species is the Bohr theory not applicable? He H Li 2+ He + What is the frequency of light having a wavelength of 500 nm ? 6 10 14 Hz 6 10 15 Hz 1.5 10 14 Hz 3 10 14 Hz The dimensions of the Rydberg constant ( R ) are: [L -1 ] [L] [M L 2 T -1 ] Dimensionless If a 0 is the radius of the first Bohr orbit of Hydrogen, the radius of the n=2 orbit of the He + ion is: 2a 0 a 0 4a 0 0.5a 0 What is the ratio of Kinetic Energy to Total Energy for an electron in any Bohr orbit of a Hydrogen atom? -1 1 0.5 -0.5 For the Balmer series in the spectrum of the hydrogen atom, the values of the lower energy level ( n 1 ) and the higher energy levels ( n 2 ) are respectively: n 1 = 2, n 2 = 3, 4, 5, n 1 = 1, n 2 = 2, 3, 4, n 1 = 3, n 2 = 4, 5, 6, n 1 = 4, n 2 = 5, 6, 7, The splitting of spectral lines of an atom when subjected to an external electric field is known as: Stark effect Zeeman effect Raman effect Photoelectric effect What is the correct value of the Rydberg constant ( R H ) in terms of cm -1 ? 109677 cm -1 1096.77 cm -1 1.097 10 7 cm -1 1.097 10 -7 cm -1 The ratio of the energy of a photon of wavelength 2000 to that of wavelength 4000 is: 2 0.5 4 1 The value of the wave number ( ) for the first line in the Lyman series of H -atom is: 3R H 4 5R H 36 8R H 9 R H Which of the following electronic transitions in a Hydrogen atom involves the largest amount of energy? n=2 to n=1 n=3 to n=2 n=4 to n=3 n=5 to n=4 If the threshold wavelength ( 0 ) for a metal is 600 nm , what is the work function ( ) of the metal? ( hc 1240 eV nm ) 2.07 eV 1.03 eV 3.12 eV 0.51 eV In a Hydrogen-like atom, the energy of an electron in the 2 nd orbit is -13.6 eV . What is the energy in the 4 th orbit? -3.4 eV -6.8 eV -1.51 eV -27.2 eV The number of waves made by an electron in the 4 th orbit of a Hydrogen atom is: 4 2 8 16 Which of the following transitions in the Hydrogen spectrum falls in the Brackett series? n=5 n=4 n=4 n=3 n=3 n=2 n=2 n=1 Based on equation E = -2.178 10 -18 J ( Z 2 n 2 ) certain conclusions are written. Which of them is not correct? The negative sign in equation simply means that the energy of electron bound to the nucleus is lower than it would be if the electrons were at the infinite distance from the nucleus Larger the value of n , the larger is the orbit radius Equation can be used to calculate the change in energy when the electron changes orbit For n = 1 , the electron has a more negative energy than it does for n = 6 which means that the electron is more loosely bound in the smallest allowed orbit Which of the following series of transitions in the spectrum of hydrogen atom fall in visible region? Brackett series Lyman series Balmer series Paschen series If radius of second Bohr orbit of the He+ ion is 105.8 pm, what is the radius of third Bohr orbit of Li 2+ ion? 15.87 pm 1.587 pm 158.7 Å 158.7 pm The radius of inner most orbit of hydrogen atom is 5.3 10 -11 m . What is the radius of third allowed orbit of hydrogen atom? 0.53 Å 1.06 Å 1.59 Å 4.77 Å The splitting of spectral lines in the presence of an external magnetic field is known as: Zeeman effect Stark effect Photoelectric effect Compton effect The work function of a metal is 4.2 eV . If the radiation of wavelength 2000 Å falls on the metal, then the kinetic energy of the fastest photoelectron is: 2.0 eV 1.6 eV 0.2 eV 6.2 eV In a hydrogen atom, the transition that emits radiation of the highest frequency is: n=2 n=1 n=6 n=2 n=1 n=2 n=2 n=6 The radius of the first Bohr orbit of a hydrogen atom is r . The radius of the third Bohr orbit of the Li 2+ ion is: 3r r 9r r 3 Which of the following transitions will have the highest energy in a hydrogen atom? n=2 to n=1 n=3 to n=2 n=4 to n=3 n=5 to n=4 How many spectral lines are produced when an electron jumps from the n=5 to the n=1 shell in a hydrogen atom? 10 15 4 6 The energy of one mole of photons of radiation whose frequency is 5 10 14 Hz is: ( h = 6.626 10 -34 J h s, N A = 6.022 10 23 mol -1 ) 199.51 kJ/mol 19.95 kJ/mol 3.31 10 -19 J/mol 1.99 10 -20 kJ/mol According to Bohr's model, the velocity of an electron in the n th orbit ( v n ) is proportional to: Z/n n/Z Z 2/n n 2/Z What is the wavelength of the limiting line (shortest wavelength) of the Lyman series for hydrogen? ( R H is Rydberg constant) 1/R H R H 4/R H 2/R H The main limitation of the Bohr model of the atom is: It cannot explain the spectra of multi-electron atoms It violates the Heisenberg Uncertainty Principle It assumes electrons move in fixed circular orbits All of the above The wavelength of the first line of the Paschen series in a hydrogen atom is ( R is the Rydberg constant): 144 7R 7R 144 16 3R 3R 16 The series of lines in the hydrogen spectrum obtained when the electron jumps from higher orbits to n=4 is called: Brackett series Paschen series Pfund series Lyman series What is the maximum wavelength of light required to ionize a hydrogen atom in its ground state? (Ionization Energy = 13.6 eV ) 912 1216 825 456 The ratio of the radius of the n=2 orbit of He + to the n=3 orbit of Li 2+ is: 2:3 4:9 1:1 3:2 The value of the Bohr radius for the hydrogen atom is 0.529 . The first excitation potential of H -atom is: 10.2 V 13.6 V 3.4 V 1.89 V Which of the following is the correct order of the increasing wave number of the given radiations? Radio waves < Infrared < Ultraviolet < X-rays X-rays < Ultraviolet < Infrared < Radio waves Ultraviolet < X-rays < Radio waves < Infrared Infrared < Radio waves < X-rays < Ultraviolet Calculate the radius of the n=3 orbit of Be 3+ ion if the radius of the first orbit of H atom is 0.529 Å . 1.19 Å 0.529 Å 2.11 Å 4.76 Å The energy of an electron in the ground state of H atom is -13.6 eV . The energy of an electron in the first excited state of Li 2+ is: -30.6 eV -13.6 eV -27.2 eV -54.4 eV If the wavelength of the first line of the Balmer series in Hydrogen is 6563 Å , the wavelength of the first line of the Balmer series in He + is approximately: 1641 Å 6563 Å 3281 Å 820 Å What is the ratio of the velocity of an electron in the first Bohr orbit of the Hydrogen atom to its velocity in the third Bohr orbit of the Li 2+ ion? 1:1 1:3 3:1 9:1 The binding energy of an electron in the n=2 orbit of a Hydrogen atom is: 3.4 eV 13.6 eV 1.51 eV 10.2 eV In the ground state of the Hydrogen atom, the Potential Energy ( U ) of the electron is related to its Total Energy ( E ) by which relation? U = 2E U = E U = E/2 U = -E Which of the following series of transitions in the spectrum of hydrogen atom falls in visible region? Balmer series Lyman series Paschen series Brackett series What is the ratio of the radius of the second Bohr orbit of Hydrogen to the radius of the third Bohr orbit of Li 2+ ? 4:3 2:3 4:9 1:3 The energy of a photon is given as 3.03 10 -19 J/ atom . The wavelength of the photon is: ( h = 6.63 10 -34 J s, c = 3 10 8 m/s ) 656 nm 342 nm 458 nm 546 nm The longest wavelength in the Balmer series of the Hydrogen spectrum occurs for the transition: n=3 n=2 n=2 n=1 n= n=2 n=4 n=2 The energy of an electron in the n=4 level of He + ion is: -3.4 eV -13.6 eV -54.4 eV -1.51 eV The energy required to excite an electron from the ground state of a Hydrogen atom to the n= state (ionization) is 13.6 eV . The energy required to excite it from n=1 to n=2 is: 10.2 eV 3.4 eV 1.85 eV 12.1 eV If the total energy of an electron in a Bohr orbit of a hydrogen atom is E , what is its potential energy in that same orbit? 2E -2E E/2 -E Based on the photoelectric effect, a plot of the maximum kinetic energy ( K max ) of photoelectrons versus the frequency ( ) of incident radiation is shown. What does the intercept on the frequency axis represent? Threshold frequency ( 0 ) Work function ( ) Planck's constant ( h ) Stopping potential ( V 0 ) Which of the following electronic transitions in a hydrogen atom emits the least energetic photon? n=6 n=5 n=4 n=3 n=3 n=2 n=2 n=1 A light of frequency 1.5 0 is incident on a photosensitive material with threshold frequency 0 . If the frequency of the light is halved and the intensity is doubled, the photoelectric current becomes: Zero Doubled Quadrupled Halved The wave number of the first line of the Lyman series for the H atom is: 3R H 4 R H 4 5R H 36 8R H 9 In the context of the Bohr model, what happens to the energy difference between consecutive orbits as n increases? Energy difference decreases Energy difference increases Energy difference remains constant Energy difference first increases then decreases If the wavelength of a photon is 600 nm , what is its energy in electron volts? (Take hc = 1240 eV nm ) 2.07 eV 1.24 eV 3.10 eV 4.14 eV According to the Bohr model, the ratio of the velocities of an electron in the first, second, and third orbits of a hydrogen atom is: 1 : 1 2 : 1 3 1 : 2 : 3 1 : 4 : 9 1 : 2 : 3 If the radius of the 1 st Bohr orbit is x , then the de Broglie wavelength of an electron in the 3 rd orbit of a Hydrogen atom is: 6 x 3 x 9 x 2 x The stopping potential ( V 0 ) for photoelectrons depends on: The frequency of incident light and the nature of the metal. The intensity of incident light only. The distance between the source and the metal. The nature of the metal only. The energy of an electron in the second Bohr orbit of the hydrogen atom is -3.41 eV . The energy of an electron in the third Bohr orbit of the He + ion will be: -6.06 eV -1.51 eV -13.6 eV -0.85 eV Based on equation E = -2.178 10 -18 J (Z 2/n 2) , certain conclusions are written. Which of the following is NOT correct? Larger the value of n , the larger is the orbit radius. For n=1 , the electron has a more negative energy than it does for n=6 . The negative sign in equation simply means that the energy of electron bound to the nucleus is lower than it would be if the electron were at the infinite distance from the nucleus. Equation can be used to calculate the change in energy when the electron changes orbit. Calculate the energy in joules corresponding to light of wavelength 45 nm . (Planck's constant h = 6.63 10 -34 J s ; speed of light c = 3 10 8 m/s ) 4.42 10 -18 J 6.67 10 15 J 4.42 10 -15 J 4.42 10 -11 J If the radius of the second Bohr orbit of the He + ion is 105.8 pm , what is the radius of the third Bohr orbit of Li 2+ ion? 158.7 pm 15.87 pm 1.587 pm 1587 pm The energy of an electron in the ground state (n = 1) for He+ ion is -x J, then that for an electron in n = 2 state for Be 3+ ion in J is -x - x 9 -4x - 4 9 x The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes n = 2 n = 3 and n = 4 n = 6 transitions, respectively, is 1 4 1 36 1 16 1 9 Which electronic transition in a hydrogen atom emits a photon in the ultraviolet region? n=2 n=1 n=3 n=2 n=4 n=3 n=5 n=4 Energy and radius of first Bohr orbit of He+ and Li 2+ are [Given R H = 2.18 10 -18 J , a 0 = 52.9 pm ] E n( Li 2+ ) = -8.72 10 -16 J ; r n( Li 2+ ) = 17.6 pm E n( He+ ) = -19.62 10 -16 J ; r n( He+ ) = 17.6 pm E n( Li 2+ ) = -19.62 10 -18 J ; r n( Li 2+ ) = 17.6 pm E n( He+ ) = -8.72 10 -18 J ; r n( He+ ) = 26.4 pm E n( Li 2+ ) = -8.72 10 -18 J ; r n( Li 2+ ) = 26.4 pm E n( He+ ) = -19.62 10 -18 J ; r n( He+ ) = 17.6 pm E n( Li 2+ ) = -19.62 10 -16 J ; r n( Li 2+ ) = 17.6 pm E n( He+ ) = -8.72 10 -16 J ; r n( He+ ) = 26.4 pm A transition from n=4 to n=2 in He + ion will result in the same wavelength as which transition in H atom? n=2 to n=1 n=3 to n=2 n=4 to n=3 n=2 to n=3 The value of the wavelength of the first line in the Balmer series of the hydrogen spectrum is . The wavelength of the second line in the same series is: 20 27 27 20 3 4 5 9 What is the wave number of the shortest wavelength transition in the Paschen series of He + ion? 4R 9 R 9 9R 4 R 4 If the radius of the first Bohr orbit of the H atom is a 0 , the de Broglie wavelength of an electron in the third orbit is: 6 h a 0 3 h a 0 9 h a 0 a 0 3 In the hydrogen spectrum, the frequency of the first line of the Balmer series is u . The frequency of the first line of the Lyman series in terms of u is: 27 u/5 5 u/27 4 u 3 u/4 Calculate the frequency of the radiation emitted when an electron falls from n=2 to n=1 in a hydrogen atom. ( R H = 1.097 10 7 m -1 , c = 3 10 8 m/s ) 2.46 10 15 Hz 1.03 10 15 Hz 3.29 10 15 Hz 6.56 10 14 Hz According to the Bohr model, what is the ratio of the time period of revolution of an electron in the n=1 orbit to the n=2 orbit of a hydrogen atom? 1:8 1:4 1:2 1:1 In which of the following pairs is the energy of the first species less than that of the second in a hydrogen atom? 2s, 3p 3d, 3s 4s, 3d 2p, 2s Which of the following transitions in the hydrogen spectrum will have the same wavelength as the Balmer transition n=4 to n=2 of He + ion? n=2 to n=1 n=3 to n=2 n=4 to n=3 n=3 to n=1 According to the Einstein's photoelectric equation, the graph between the maximum kinetic energy ( K max ) of photoelectrons and the frequency ( ) of incident radiation is a straight line with a slope equal to: Planck's constant ( h ) Work function ( W 0 ) Threshold frequency ( 0 ) Charge of electron ( e ) For a hydrogen-like atom, the energy of an electron in the n th orbit is given by E n = -13.6 Z 2 n 2 eV . What is the second excitation energy for He + ion? 48.36 eV 40.8 eV 54.4 eV 13.6 eV The frequency of revolution of an electron in the n th Bohr orbit of a Hydrogen atom is proportional to: 1/n 3 1/n 2 n 2 Z/n The value of the Rydberg constant ( R H ) is 1.097 10 7 m -1 . What is the wave number of the last line of the Lyman series in a hydrogen spectrum? 1.097 10 7 m -1 0.25 10 7 m -1 4.38 10 7 m -1 0.548 10 7 m -1