falas 1 Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom ‘When an c-particle of mass m moving with velocity ¥ bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on mas 1 wot wom ot Or (NEET-I 2016) ‘An alpha nucleus 0 nv? bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional ta + ™ 1 . MZ wr In a Rutherford scattering experiment when a projectile of charge z, and mass M, approaches a target nucleus of charge 2: and mass M,the distance ‘of closest approach is ry The energy of the projectile is (a) directly proportional to (b) inversely proportional to &; (©) diteetly proportional to mass M, (@) directly proportional to M, x M, (2009) ‘An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The b Force F between the two fs a) eS by -KSe 7 eo ¢2003) ED Atomic Spectra ‘The ratio of wavelengths of the last ine of Balmer series and the last line of Lyman series is @t (oy 4 (05 a2 (NBET 2017) Given the value of Rydberg constant is 107 m', the ‘wave number of the last line of the Balmer series in hydrogen speetrum will be (a) 0.25% 10° (b) 25 x 107 (©) 0035 % 104m! (d) 05 x 10° (NEET-1 2016) Ratio of longest wavelengths corresponding to Lyman. and Ban spectrum is @Z 9 (NEET 2013) ‘The wavelength of the first line of Lyman series for hydrogen atom is equal to that af the second line of Balmer series for a hydrogen like ion. ‘The atornic number Z of hydrogen like ion is, ws (bya 1 (a2 (2011) Which source is associated with « line emission spectra (a) Plectric fire (¢) Red trafic light BD Bohr Model of the Hydrogen Atom 10, For which one of the following, Bohr model is not valid? (a) Hydrogen atom {(b) Singly tonised helium atorn (He!) {) Deuteron atom (d) Singly ionised neon atom (Ne*) ‘The total energy of an electron in an orbit is — 3.4 eV. Is kinetic and potent ae, respectively Ab) Neon street sign (a) Sun (1993) (NEET 2020) om in an energiesAtoms () Me adeV —(b) -34 0-34 (0 =3AeV~6.8eV (d) 34 eV, ~6.8eV (NEET 2019) “The radius of the first permitted Bohr orbit for the electron, in a hydrogen atom equals 0.51 A and its ground state energy equals ~13.6 eV. If the electron in the hydrogen atom is replaced by muon (Wr) [charge same as electron andl mass 207 m, the first Bohr radius and ground state energy will be (a) 053 x 10"? m, -3.66V (b) 25.6 x 10" m, -28eV (0) 256 x 10-! m, -2.8keV (d) 256 x 10°? m, -13.6€V (Odisha NEET 2019) “The ratio of kinetic energy tothe total energy of an €lectron in a Bohr orbit of the hydrogen atom, is bt jt (NEET 2018) Consider 3* orbit of He’ (Helium), using non-relativistic approach, the speed of electron in this orbit will be [given K'= 9 x 10° constant, Z = 2 and ht (Planck's constant) = 6.6% 10 Fs) (a) 073% 10° m/s (b) 3 (0) 292% 10' m/s (d) 1.46 10° ms (2015. ‘An electron in hydrogen atom makes a transition nn, > nt, where n, and n, are principal quantum numbers of the two states, Assuming Bohr's model to be valid, the time period of the electron in the initial state is eight times that in the final state, The possible values of m, and n are (@) ms6andn=2 — (b) m=8andny=1 (0 m=Bandn=2 — (d) med and ny=2 (Karnataka NEET 2013) ‘Monochromatic radiation emitted when electron (on hydrogen atom. jumps from first excited to the ground state itradiates a photosensitive material. “The stopping potential is measured to be 3.57 V. The threshold frequency of the material is, (a) 4x 10" He (b) 5x 10" Ha (o) 16 10 He (4) 2.5% 10 He (2012) ‘An electron in the hydrogen atom jumps from excited state to the ground state. The wavelength so emitted illuminates a photosensitive material having, work function 2.75 eV. If the stopping potential of the photoelectron is 10 V, then the value of w is (a) 2 (b) 3 (o 4 (ds (Mains 2011) Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohe’s atomic model? (0) 065eV 19ev (@ Mev (@) 136eV (Mains 2011) The energy of.a hydragen atoms in the ground state is 13.6 eV. The energy of a He’ ion in the first excited state will be (a) -13.6eV (b) -27.2 eV (0) S44eV (@)-68eV (2010) “The electron in the hydrogen atom jumps from excited state (n= 3) to its ground state (n= 1) and the photons thus emitted irradiate a photosensitive ‘material, Ifthe work function of the mater 5.1 eV, the stopping potential is estimated to be (the ‘energy of the electeon in fy 5aV (b) 1.1 (172 @7V_— (Mains 2010) “The ground state energy of hydrogen atom is =186 eV. When its electron is in the first excited state its excitation energy is fa) 10.2eV (b) 0 (34 (W) 68 eV (2008) “The total energy of electron in the ground state of hydrogen atom is -13.6 eV. The kinetic energy of an electron in the frst excited state is @) 68V, (b) 136eV (17 (W) 34ev (2007) “The total energy of an electron in the first excited state of hydrogen atom is about -3. eV. Its kinetic ‘energy in this state is (a) 34eV (b) 68 eV {@) -34eV (@) -68eV The Bohr model of atoms (a) Assumes that the angular momentum of electrons is quantized. {b) Uses Einstein's photoelectric equation, (6) Predicts continuousemission spectra for atoms, {d) Predicts the same emission spectra forall types (2004) the following systems will the radius bit (n = 1) be minimum? {@) doubly ionized lihiurm {) singly ionized helium {6} deuterium atom (d) hydrogen atom (2003) “The energy of hydrogen atom in 1 orbit is E, (b) BA (ER “The life span of atomic hydrogen is {a} fraction of one second110 28. 31. 32. 33. 35. In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If 4y is the radius of the ground state orbit, m is ‘mass and e is the charge on the electron and e, is the vacuum permittivity, the speed of the electron is. : ‘ © Fc Tom (Oo (d) femswaom (1998) . The energy of the ground electronic state of hydrogen atom is 13.6 eV. The energy of the first excited state will be (a) -272eV (b) -52.4eV (o) -34eV (d) -68eV (1997) When hydrogen atom is in its first excited level, its radius is... of the Bohr radius. (a) twice (b) 4 times (©) same (d) half (1997) According to Bohr's principle, the relation between principal quantum number (n) and radius of orbit (ris 1 1 (@) ret ) ret 7 2 (ren (@) rem (1996) When a hydrogen. atom is raised from the ground state to an excited state, (a) both K-E. and P-E. increase (b) both KE. and PLE. decrease (c) the PLE. decreases and KE. increases (d) the PE. increases and KE. decreases. (1995) In terms of Bohr radius aa, the radius of the second Bobr orbit ofa hydrogen atom is given by (a) day (b) Bay (Vay (d) 2a (1992) ‘The ionization energy of hydrogen atom is 13.6 eV. Following Bobr’s theory, the energy corresponding to a transition between 3" and 4* orbits (a) 3.40eV (b) L51eV (c) 0.85 eV (d) 0.66eV (1992) ‘The ground state energy of H-atom is -13.6 eV. The energy needed to ionize H-atom from its second excited state (a) LsleV (b) 34eV (0) 13.6eV (q) none of these (1991) ‘To explain his theory, Bohr used (a) conservation of linear momentum (b) quantisation of angular momentum (©) conservation of quantum frequency (2) none of these (1989) \WcbG NEET-AIPMT Chaplerwise Topicwise Solutions IE 37. The ionisation energy of hydrogen atom is 13.6 eV, the ionisation energy of a singly ionised helium atom would be (@) 13.6eV (b) 272eV (© 68eV (@) 544ev (1988) BEB the Line spectra of the Hydrogen Atom 38. fan electron in a hydrogen atom jumps from the 3" orbit to the 2" orbit, itemits a photon of wavelength 2. When it jumps from the 4* orbit to the 3° orbit, the corresponding wavelength of the photon will be @ 2 & 22 © 2%, @ Mr 8 i6 7 B (NEET-II 2016) 39. Hydrogen atom in ground state is excited by a ‘monochromatic radiation of A = 975 A. Number of spectral lines in the resulting spectrum emitted will be @3 (b) 2 ws (a) 10 (2014) 40. Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited tothe first excited state. The ratio of emitted in the two cases is z z a 20 @2 wZ ©2 w? 5 2 3 7 2012) 41. An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon. emission will be 2ARR oy 25hR 25m 24m ator ao os (2012) (mis the mass of the electron, R Rydberg constant and h Planck’s constant) 42. The transition from the state n= 3 tom = lina hydrogen like atom results in ultraviolet radiation. Infrared radiation willbe obtained in the transition from @231 (b) 332 (J 472 (d) 43 (Mains 2012) 43. ‘Theionization energy of the electron in the hydrogen atom in its ground 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 (a) n=3ton= states (b) n=2tom=1 states (9) n=4ton=3states (d) n= 3 ton = 2 states (2009)Atoms 44. Ionization potential of hydrogen atom is 13.6 eV. 45. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohs theory, the spectral lines emitted by hydrogen will be (a) one (b) two (©) three (@) four (2006) Energy levels 4, B and C of a certain atom corresponding to increasing values of energy ic. By < Be If ye and hy ate weelengh of an Which of the following spectral lines will occur in the absorption spectrum? (b) 1.23456 @ 146 (1995) Hydrogen atoms are excited from ground state of the principle quantum number 4. Then the number of spectral lines observed will be @3 ) 6 Os (@2 (1993) ations corresponding to transitions C to B, | [EX de Broglie’s Explanation of Bohr's Btodand Cw sropectne cha be owing Second Postulate of Quantisation relations is correct? 51. Consider an electron in the n™ orbit of a hydrogen (0) Anat ) a= atom in the Bohr model. The circumference of Athy the orbit can be expressed in terms of de Broglie (Aththye0 A AAA HAE ‘wavelength A of that electron as (2005, 1990) | (a) (0.529)nd, () in 46, Maximum frequency of emission is obtained for the (© (3.6) (dm (1990) transition (@) n=2t0n=1 —— (b) n=6t0n=2 EE) «Rays (©) n=lton=2 (@) m=2ton=6 (2000) | 52. The interplanar distance in a crystal is 2.8 x 10 m, 47, When an electron does transition from ‘The value of maximum wavelength which can be n= 4ton-= 2, then emitted line spectrum will be diffracted (@) first line of Lyman series (@) 28x10%m (b) 56x 10%m (b) second line of Balmer series (© 14x 10m (d) 7.6x10%m (2001) (c) first line of Paschen series 53. The minimum wavelength of the X-rays produced by (d) second line of Paschen series. (2000) electrons accelerated through a potential difference 48. An electron makes a transition from orbit of V volts is directly proportional to n= 4 to the orbit n = 2 of a hydrogen atom. What 1 1 2 is the wavelength of the emitted radiations? OF OF OW wy (1986) (R= Rydberg’s constant) 1 i 16 54. The figure represents the observed intensity of OR OF OF os ‘X-rays emitted by an X-ray tube,1 as a function of 5 2k (1995) wavelength. The sharp peaks A and B denote 49, The figure indicates the energy level diagram of an A atom and the origin of six spectra lines in emission e (eg. line no, 5 arises from the transition from level B i to). £ © Woda Ly (a) white radiations (b) characteristic radiations 4 (©) band spectrum (4) continuous spectrum 7% (2995) ANSWER KEY L@2 @% @ 4 @s % 6 @ 72 O & M2 & 0 @ U. fd) 12 ( 13. () Mm. (d) 15. @) 16 () 172 ( 1 (©) 1% (a) 20 (dd) a. (@) 22d) 23. G@) 2 (a) 25. (@) 26 (@) 7 @ 2. G@ B (©) 3. 31. (2) 32. @) 33. @) 3. @) 35. G@) 36.) 37. @) 38. 3% (| 1 4. @ 2 @ 8 © 4 © 5 0) 4 @ 47 0) & @ 9% © 50 ) sl. (d) 52 (b) 53. () St)