Atomic Models (Thomson Rutherford) — Practice Questions

Free NEET Physics multiple-choice questions on Atomic Models (Thomson Rutherford). Attempt each question and reveal the answer with a full explanation.

An -particle consists of: 2 protons and 2 neutrons 2 protons and 4 neutrons 1 proton and 1 neutron 4 protons and 2 neutrons The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is 2 : -1 1 : -1 1 : 1 1 : -2 The total energy of an electron in an atom in an orbit is -3.4 eV. Its kinetic and potential energies are, respectively: 3.4 eV, 3.4 eV -3.4 eV, -3.4 eV -3.4 eV, -6.8 eV 3.4 eV, -6.8 eV For which one of the following, Bohr model is not valid ? Singly ionised helium atom ( He + ) Deuteron atom Singly ionised neon atom ( Ne + ) Hydrogen atom Let T 1 and T 2 be the energy of an electron in the first and second excited states of hydrogen atoms, respectively. According to the Bohr’s model of an atom, the ratio T 1 : T 2 is 4 : 1 4 : 9 9 : 4 1 : 4 In the first excited state of hydrogen atom, the energy of its electron is -3.4 eV . The radial distance of the electron from the hydrogen nucleus in this case is approximately: (Take 1 eV =1.6 10 -19 J , e=1.6 10 -19 C and 1 4 0 =9 10 9 N m 2/C 2 ) 2.1 10 -8 m 2.1 10 -10 m 2.1 10 -11 m 2.1 10 -9 m In Rutherford's alpha-particle scattering experiment, what will be the correct angle for which the impact parameter is zero? 180 90 0 45 An alpha nucleus of energy 1 2 mv 2 bombards a heavy nuclear target of charge Ze . Then the distance of closest approach for the alpha nucleus will be proportional to: 1/m v 2 1/Ze m For a given scattering angle in Rutherford scattering, the impact parameter b is proportional to: ( /2) ( /2) ( /2) ( /2) In Rutherford's alpha-scattering experiment, what fraction of alpha particles were scattered at angles greater than 90 ? About 1 in 8000 About 1 in 10 About 1 in 100 About 1 in 10 6 In a Rutherford scattering experiment, the distance of closest approach for an -particle of energy E hitting a nucleus of atomic number Z is r 0 . If an -particle of energy 2E hits a nucleus of atomic number 2Z , the distance of closest approach will be: r 0 2r 0 4r 0 r 0/2 In the Rutherford scattering experiment, the number of alpha particles scattered at an angle of 180 is minimum because: The probability of a head-on collision is very low. The nucleus is very small. The alpha particles are negatively charged. Most of the atom is empty space. The distance of closest approach of an -particle of energy E to a nucleus is r 0 . If the energy of the -particle is doubled, the distance of closest approach becomes: r 0/2 2r 0 r 0/4 4r 0 Which of the following atoms has the lowest ionization potential? O (Oxygen) H (Hydrogen) He (Helium) Li (Lithium) In Rutherford's -particle scattering experiment, the number of particles scattered at an angle is N . If the scattering angle is increased from 60 to 120 , the ratio of the number of scattered particles N 120 /N 60 will be: 1/9 1/3 9 3 Energy levels A, B and C of a certain atom correspond to increasing values of energy i.e. E A < E B < E C . If 1 , 2 and 3 are wave lengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct - 3 = 1 + 2 1 + 2 + 3 = 0 3 2 = 1 2 + 2 2 3 = 1 2 1 + 2 Ionization potential of hydrogen atom is 13.6eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emitted by hydrogen will be:- Two Three Four One The ionization energy of the electron in the hydrogen atom in its grounds state is 13.6 eV . The atoms are excited to higher energy levels to emit radiations of 6 wavelengths. Maximum wavelength of emitted radiation corresponds to the transition between : n=4 to n=3 states n=3 to n=2 states n=3 to n=1 states n=2 to n=1 states Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is 5 27 3 23 7 29 9 31 Hydrogne atom is ground state is excited by a monochromatic radiation of = 975 , . Number of spectral lines in the resulting spectrum emitted will be 3 2 6 10 If the longest wavelength in the ultraviolet region of hydrogen spectrum is o then the shortest wavelength in its infrared region is : 46 7 o 20 3 o 36 5 o 27 4 o In hydrogen spectrum, the shortest wavelength in the Balmer series is . The shortest wavelength in the Bracket series is 2 4 9 16 In the Rutherford scattering experiment, the impact parameter b = 0 corresponds to a scattering angle of: 180 0 90 45 Given below are two statements: Statement I: Atoms are electrically neutral as they contain equal number of positive and negative charges. Statement II: Atoms of each element are stable and emit their characteristic spectrum. In the light of the above statements, choose the most appropriate answer from the options given below. Both Statement I and Statement II are correct Both Statement I and Statement II are incorrect Statement I is correct but Statement II is incorrect Statement I is incorrect but Statement II is correct Match List I with List II. array llll ; & List I; (Spectral Lines of Hydrogen for transitions from) & ; & List II; (Wavelengths (nm)) A. & n 2 = 3 to n 1 = 2 & I. & 410.2 B. & n 2 = 4 to n 1 = 2 & II. & 434.1 C. & n 2 = 5 to n 1 = 2 & III. & 656.3 D. & n 2 = 6 to n 1 = 2 & IV. & 486.1 array Choose the correct answer from the options given below: A-II, B-I, C-IV, D-III A-III, B-IV, C-II, D-I A-IV, B-III, C-I, D-II A-I, B-II, C-III, D-IV A particle of mass m is moving around the origin with a constant force F pulling it towards the origin. If Bohr model is used to describe its motion, the radius of the n th orbit and the particle's speed v in the orbit depend on n as r n 4/3 ; v n -1/3 r n 1/3 ; v n 1/3 r n 1/3 ; v n 2/3 r n 2/3 ; v n 1/3 In the Geiger-Marsden scattering experiment, if the number of -particles scattered at an angle of 60 is 100 per minute, then the number of -particles scattered per minute at an angle of 90 is approximately: 25 50 12.5 400 According to the Heisenberg Uncertainty Principle, an electron cannot exist inside a nucleus because its calculated kinetic energy would be approximately: Several hundred MeV 13.6 eV 1 MeV Zero The magnetic field at the center of a hydrogen atom due to the motion of the electron in the n th orbit is proportional to: n -5 n -3 n -2 n -1 The magnetic field induction at the center of a hydrogen atom due to an electron revolving in the n th orbit is proportional to: n -5 n -3 n 3 n 5 In an -particle scattering experiment, the number of particles scattered at an angle = 90 is 56 per minute. The number of particles scattered at an angle = 60 per minute will be: 224 112 14 28 The magnetic moment ( ) of an electron revolving in the n -th Bohr orbit of a hydrogen atom is proportional to: n n 2 1/n n 3 In a hydrogen atom, the electron revolves in an orbit of radius r . The magnetic field B produced at the center of the nucleus due to the motion of the electron is proportional to: 1/n 5 1/n 3 1/n 2 1/n 4 The total energy of an electron in the first excited state of hydrogen atom is about -3.4 eV . Its kinetic energy in this state is- -6.8 eV 3.4 eV 6.8 eV -3.4 eV The ratio of the magnetic field at the center of the nucleus in the first orbit to the second orbit of a hydrogen atom is: 32:1 8:1 16:1 4:1 The magnetic field B produced at the center of the nucleus by an electron revolving in the ground state of a hydrogen atom is B 0 . The magnetic field produced in the n=2 state is: B 0/32 B 0/8 B 0/16 B 0/64 In Geiger-Marsden experiment, the number of scattered -particles N( ) is plotted as a function of scattering angle . Which of the following options represents the correct plot? Graph (1) Graph (2) Graph (3) Graph (4) The energy of second Bohr orbit of the hydrogen atom is -328 kJ mol -1 ; hence the energy of fourth Bohr orbit would be :- -1312 kJ mol -1 -82 kJ mol -1 -41 kJ mol -1 -164 kJ mol -1 In a discharge tube ionization of enclosed gas produced due to collisions between:- Positive ions and neutral atoms/molecules Negative electrons and neutral atoms/molecules Photons and neutral atoms/molecules Neutral gas atoms/molecules The total energy of electron in the ground state of hydrogen atom is -13.6 eV. The kinetic energy of an electron in the first excited state is 6.8 eV 13.6 eV 1.7 eV 3.4 eV. In a Rutherford scattering experiment when a projectile of charge Z 1 and mass M 1 approaches a target nucleus of charge Z 2 and mass M 2 , the distance of closest approach is r 0 . The energy of the projectile is : Directly proportional to mass M 1 Directly proportional to M 1 M 2 Directly proportional to Z 1Z 2 Inversely proportional to Z 1 Given the value of Rydberg constant is 10 7 m -1 , the wave number of the last line of the Balmer series in hydrogen spectrum will be :- 0.025 10 4 m -1 0.5 10 7 m -1 0.25 10 7 m -1 2.5 10 7 m -1