Atomic Structure Questions and Answers

A proton of mass mp is moving with an initial velocity vo colliding with a helium atom of mass 4 mp at rest If the proton leaves the point of collision at an angle 4 relative to the path of motion Find the final velocity of both particles in the case of inelastic collision and that Q 1 4 KEp

spontaneously decays releasing a Helium nucleus in the 236 Th a This is an example of alpha decay resulting in 90 238 U A nucleus of Uranium 238 924 process Which statement is true b This is an example of beta decay resulting in 234 c This is an example of alpha decay resulting in Th 242 Pu 94 234 d This is an example of alpha decay resulting in 90 Th 236 e This is an example of gamma decay resulting in 90 Th

1 If one takes into account finite mass of the proton the correction to the binding energy of the hydrogen atom is approximately Mass of proton 1 60x10 27 kg mass of electron 9 10 10 21 kg KVPY 2016 a 0 06 0 0097 0 0006 b d 0 00

The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1 6 x 10 16 s The frequency of revolution of the electron in its first excited state in s 1 is 1 6 2 x 1015 2 5 6 1012 3 7 8 x 1014 4 1 6 1014 C

Let Fpp Fpn and Fnn denote the nuclear force between proton proton proton neutron and neutron neutron pair respectively When separation is 1 fm O Fpp Fpn Fnn O Fpp Fpn Fnn Fpp Fpn Fnn O Fpp Fpn Fnn Marks

16m 45 Every series of hydrogen spectrum has an upper and lower limit in wavelength The spectral series which has an upper limit of wavelength equal to 18752 is Rydberg constant R 1 097 x 107 A Balmer series C Paschen series per metre MP PMT 1993 B Lyman series Pfund series D

V is the frequency of the series limit of Lyman series V is the frequency of the first line of Lyman series and V3 is the frequency of the series limit of the Balmer series Then O V V V3 O V V V3 O 1 1 V2 V1 V3 Fo

Q 6 Moderate 1 01 55 A hydrogen like atom of atomic numbe Z is in an excited state of quantum number 2n It can emit a maximum energy photon of 204 eV If it makes transition to quantum state n a photom of energy 40 8 eV is emitted The value of n will be

The ionisation potential of hydrogen atom is 13 6 eV An electron in the ground state of a hydrogen atoms absorbs a photon of energy 12 75 eV How many different spectral line can one expect when the electron make a downward transition O 1 O4

A heated plate 20 by 20 cm is inclined at an angle of 60 with the horizontal and placed in water Approximately constant heat flux conditions prevail with a mean plate temperature of 40 C and the heated surface facing downward The water temperature is 20 C Calculate the heat lost by the plate

The Biding energy per nucleon of Li and He nuclei are 5 60 MeV and 7 06MeV respectively In the nuclear reaction Li H2He Q the value of energy Q released is 3 8 4 MeV 1 19 6 MeV 2 2 4 MeV 4 17 3 MeV Two smooth and similar right angled prisms are arranged on a smooth horizontal plane as shown in the figure The lower prism has a mass 3 times that of the upper prism The prisms are held in an initial

34 What should be the ratio of minimum to maximum wavelength of radiation emitted by transition of an electron to ground state of Bohr s hydrogen atom in lymen series 1 3 43 18 2 4 1438

15 The energy levels of a hypothetical one atom are shown in figure below 0 eV 0 80 eV 1 45 eV 3 08 eV 5 30 eV 15 6 eV n n 5 n 4 n 3 n 2 n 1 i Find the ionization potential of the atom ii Find the short wavelength limit of the series terminating at n 2 iii Find the wave number of the photons emitted for the transition n 3 to n 1 iv The initial kinetic energy of an electron is 11 eV and it interacts with the hypothetical one electro ntom Determine the minimum energy carried by the electron after interaction

PASSAGE An electron m 9 109 10 31 kg is confined in a one dimensional infinite square well of width L 10 nm determine energy for first excited energy state OPTIONS 6 038 10 22 J 24 15 10 22

ASSAGE n electron m 9 109 10 31 kg is confined in a one dimensional infinite square well of width L 0 nm Choose the correct options Marks 2 determine uncertainty in velocity OPTIONS 5791 m s 9010 m s

The kinetic energy of an electron is 5 eV Calculate the de Broglie wavelength associated with it h 6 6 x 10 34 Js m 9 1 x 10 1 kg Question Type Single Correct Type 1 5 47 2 10 9 3 2 7

a 15 Energy levels A B C of corresponding to increasing values of energy i e EA EB Ec If A A2 A3 are the wavelength of radiations corresponding to the transitions C to B B to A and C to A respectively Which of the following statements is correct I 2 22 1 23 2 2 3 2 2 2 0 3 C B A 2122 2 2 4 2 2 2 2 3 23

electron m 9 109 10 31 kg is confined in a one dimensional infinite square well of width L ama determine energy for ground energy state OPTIONS 4 10 11 J 7 8 10 20 J

The first three spectral lines of H atom in the Balmer series are given A1 A2 A3 considering the Bohr atomic model the wave lengths of first and third spectral lines are related by afactor of approximately x mathongo mathongo mathonge mathon mothongs x10 The value of x to the nearest integer is

0 The vapour pressure of a pure liquid solvent X is decreased to 0 60 atm from 0 80 atm on addition of a non volatile substance Y The mole fraction of Y in the solution is 1 0 20 1905 2 0 25 6410 25

03 Suppose a hydrogen like atom whose ene 13 622 nth excited state is given by En When this excited atom makes a transition from excited state to ground state most energetic photons have energy Emax 52 224 eV and least energetic photons have energy Emin 1 224 eV The atomic number of atom is 1 52 224 ev A 5 B 4 C 2 D None of these E nr Et nr n 2 n 1 2 1 224 eV

Calculate the potential required to stop all the electrons when a light of wavelength 176 nm shines on a metal whose work function is 6 5 eV er a 0 30 eV b 0 65 ev c 0 56 eV d 0 65 eV OA OB

56 A proton is about 1840 times heavier than a electron When it is accelerated by a potenti difference of 1 kV its kinetic energy will be 1 1840 keV 2 1 1840 keV 21 1 030 1

Suppose frequency of emitted photon is fo when electron of a stationary hydrogen atom jumps from a higher state m to a lower state n If the atom is moving with a velocity v c and emits a photon of frequency f during the same transition then which of the following statements is not possible 1 f may be equal to fo 2 f may be greater than fo 3 f may be less than fo 4 f cannot be equal to f

23 In the following atoms and molecules transition from n 2 to n 1 the spectr minimum wavelength will be produced by 1 Hydrogen atom 2 Deuterium atom 3 Unionized helium lithium

If and 2 are respectively the wavelengths of the series limit of Lyman and Balmer series of Hydrogen atom then the wavelength of the first line of the Lyman series of the H atom is A B 2 C 22 21 2 22 D 22 21

The compound unstable nucleus 236U often decays in accordance with the following reaction U10 92 other particles In the nuclear reaction presented above the other particle might be Question Type Single Correct Type 1 2 3 an alpha particle which consists of two protons and two neutron two protons one proton and one neutron 94 Xe tay Sr

3 3r If the de Broglie wavelength of a proton is 10m the electric potential through which it must have been accelerated is 1 4 07 10 V 2 8 2 10 V 3 8 2x10 V 4 4 07 10 V Radiations of two photon s energy twice and ten times the work function of metal are incident on the metal surface successively The ratio of maximum velocities of photoelectrons emitted in two cases is

100 The output X of the logic circuit shown in figure will be mo RAINEET 2013 A Be 101 a X A B b X A B c X A B d X A B Laiton In an unbiased p n junction holes diffuse from

16 A double charged lithium atom is equivalent to hydrogen whose atomic number is 3 The wavelength of required radiation for emitting electron from first to third Bohr orbit in Litt will be lonisation energy of hydrogen atom is 13 6eV UPSEAT 1999 a 182 51 c 142 25 b 177 17 d 113 74

A charge of mass m and charge q is accelerated from res in a uniform electric field of strength E The velocity acquired by it two second after released will be qE 2qE m 4qE m 2qE m

An electron of kinetic energy 100 eV collides with a stationary helium ion He in its ground state and excites it to a higher level After collision He ion emits two photons in succession with wavelengths 1085 A and 304 A Find the kinetic energy of electron after collision Neglect the recoil speed of He ion

10 An electron moves along a metal tube with a variable cross section as show in figure How will its velocity change when it approaches the neck of the tube 0 a Velocity will increase b Velocity will decrease c Velocity will remain same d Information is not sufficient

4 When an a particle collides with a stationary lithium nucleus the following nuclear reaction may take place 4He 7Li 10B n If Q value of this reaction is E 2 87 MeV find the minimum value of kinetic energy of incoming a particles required for the reaction 5 Nuclei of deuterium D 2H and tritium T H can fuse according to the

5 If an orbital electron of the hydrogen atom jumps from the ground state to a higher energy state its orbital speed reduces to half its initial value If the radius of the electron orbit in the ground state is r then the radius of the new orbit would be a 2r c 8r 6 4r d 16r

A hydrogen like atom of atomic number Z is in excited state of quantum number 2n It can emit a maximum energy photon of 204 eV If it makes a transition to a quantum number n a photon of energy 40 8 eV is emitted A The value of n is 2 B The value of Z is 3 C The minimum energy that can be emitted by this atom during de exitation is 10 57 eV D The ground state energy for this atom is 217 6 eV

SolveLancer Test The exchange forces i Can be explained by classical theory ii Can be explained by only quantum mechanics iii sometimes results in the appearance of antiferromagnetics SolveLancer Tes a i is correct but ii is false b ii is correct but iii is false c iii is false and i is correct d ii is correct but i is false

5 Like angular momentum which of the following is quantised for electron in Bohr s model of H atom 1 Kinetic energy 3 Speed 2 Radius 4 Magnetic moment

3 a Two stable isotopes of lithium Li and Li have respective abundances of 7 5 and 92 5 These isotopes have masses 6 01512 u and 7 01600 u respectively Find the atomic mass of lithium no 10 p 11 r

A Bohr hydrogen atom at rest in free space undergoes a transition from the energy level n 2 to n 1 emitting a photon in the positive x direction Since this photon has momentum the atom must recoil in the negative x direction Find the recoil velocity of the atom A 125 cm sec C 225 cm sec B 325 cm sec D 425 cm sec

An electron of mass m and charge e accelerated from rest through a potential difference Vin vacuum The fina speed of electron will be O O O lev 2e V m 02 56 hr min 12e V m

11 a By using the deBroglie relation derive the Bohr condition mur n for the angular momentum of an electron in a hydrogen atom b Use this expression to show that the allowed electron energy states in hydrogen atom can be written me En 88h n c How would this expression be modified for the case of a triply ionized beryllium atom Be Z 4 d Calculate the ionization energy in eV of Be 3 ionization energy of hydro gen 136eV

As per Pauling the radius of an a given crystal is inversely proportional to the effective nuclear charge Z Z Z 0 where o represents the screening constant The crystal structure of NaF is shown as below F Nat F Na X X F Nat Nat F 4 7 130 x The value o

c 3 2x10 8 eV d 3 3x10 8 eV 3 Find the energy of photon in watt hour for electromagnetic waves of wavelengths 3000 of wi Given h 6 6 10 34 Js b 2 1022 Wh d 1 83 1022 Wh a 2x10 22 Wh c 1 83 10 22 Wh

An electron of mass me has a speed un in the nth Bohr orbit of a hydrogen atom The normalized speed V is given as Vn un c 1 685 and the mass of the electron in the units of energy is given as Me mec 0 51 x 106 eV where e is the velocity of light in vacuum It is given that 2ehe 1 137 The Planck s constant h is given as 4 13 x 10 15 eV sec The electron makes a transition from nth orbit to the ground state of the atom What is the frequency of the emitted photon X1 3 29 x 10 5 Hz 2 3 16 x 1015 Hz X3 2 47 x 1015 Hz X 4 293 x 1015 Hz

4 A small mirror of area A and mass m is suspended in a vertical plane by means of a weightless string A beam of light of intensity I falls normally on the mirror and the string is deflected form the vertical through a very small angle a Assuming the mirror to be perfectly reflecting obtain an expression for a 21A I c mg c mg 31 c mg a C b d None of the above 21 C mg

A hydrogen atom at rest de excites from n 2 state to n 1 state if recoil of atom is not taken into account then the percentage error in momentum of photon is a x 10 7 The value of 5a is The energy equivalent of rest mass of hydrogen atom is 940 Mev

Three photons coming from excited atomic hydrogen sample are observed their energies are 12 1 eV 10 2 eV and 1 9 eV These photons must come from a Single atom c Three atoms b Two atoms d Either two or three atom TPHO As the electron in Bohr orbit of hydrogen atom passes from state n 2 to n 1 the kinetic

Bohr s atom model assumes a The nucleus is of infinite mass and is at rest b Electrons in a quantized orbit will not radiate energ c Mass of electron remains constant d All the above conditions

82 The diagram shows the path of four a particles of the same energy being scattered by the nucleus of an atom simultaneously Which of these are is not physically possible 1234 1 2 3 4 a Both 3 and 4 c Both 1 and 4 None of these b Both 2 and 3 d Only 4