Atomic Structure Questions and Answers

energy decrease If we have to apply Bohr model to a particle mass m and charge q moving in a plane und the influence of a magnetic field B the energ of the charged particle in the nth level will be 1 n 3 hqB 2xm hqB 2 n hqB 4mm hqB

13 Physi If in hydrogen atom radius of n Boh 4 Time period and frequency of revol electron in n orbit are T and f ch correct option T A 2 K 1 2 3 log log n

5 A photon of energy 70 eV collides with He ion Due to this collision He atom gets ionized The maximum kinetic energy of the emitted electron is 1 13 6 eV 3 27 2 eV 2 15 6 eV 4 31 2 eV

fork e first and rge ion 4 200 Q 38 Velocity of electron in the ground state of hydrogen atom is given by where r is radius of first orbit of hydrogen atom and m is the mass one electron 2 1 3 e 4TE mr 2 h 4 h 2 r h 2 mr

Q 1 MULTIPLE CHOICE Suppose the potential energy between electron and proton at separation is given by U klogr where k is constant If mass of electron is m then the radius of nth Bohr s orbit is Hauz gazia am g cia U klogr a fu la 7 J i k Audic ua s t ci G H m d n i c t AUT A B Directly proportional to n z Correct Answer Directly proportional to n t Inversely proportional to m a z

7 How much energy is required to take a hydroger atom from its ground state to excited state where it subsequently emits radiation of six differen wavelength 1 10 2 eV 3 12 75 eV 2 12 1 V 4 13 06 eV

Calculate for He i radius of the first Bohr orbit ii velocity of electron moving in the first orbit iii orbital frequency in the first orbit iv kinetic energy and binding energy of electron in the ground state v ionization potential and the first excitation potential vi wavelength of the resonance line emitted in the transition n 2 n 1

19 If the wavelength of first line of Blamer series is 6563 The wavelength of first line of Lyman series and Rydberg s constant respectively will be a 1215 4 1 1 10 m 1 1 b 5863 2 0 107 m c 2316 4 0 1x107m d none of these 1 DPMT 2003

8 The wavelength of the short radio waves microwaves and ultraviolet waves are A A respectively Arrange them in decreasing order 2 2 2 2 4 2 1 3

3 1 4 Hz 4 1 47 Hz 3 Energy required for the electron excitation in Li from the first to the third Bohr orbit is 1 12 1 eV 2 36 3 eV 3 108 8 eV 4 122 4 eV For a body moving along x axis the distance

11 Energy levels A B and C of a certain atom correspond to increasing values of energy i e EA EB Ec If 2 and 23 are wavelengths of radiations corresponding to transitions C to B B to A and C to A respectively which of the following relations is correct a 2 c 2 2 22 b 2 3 0 2 2 d 2

47 The total energy of a hydrogen atom in its ground state is 13 6 eV If the potential energy in the first excited state is taken as zero then the total energy in the ground state will be a 3 4 eV c 6 8 eV b d 3 4 eV 6 8 eV

24 If vis the velocity of an electron in first excited state of H atom and fis the frequency of revolution then the de Broglie wavelength of the electron will be 2 21

Kinet energ Calculate the de Broglie associated with it h 6 6 x 10 34 Js m 9 1 x 10 31 kg 1 5 47 2 10 9 2 7 12 01 electron is 5 eV wavelength

Consider the two level system shown in Fig with E 13 6 eV and E2 3 4 eV Assume A216 x 10 s a What is the frequency of light emitted due to transitions from E2 to E Assuming to have only natural broadening what is the FWHM of the emission What is the population ratio N N at T 300 K E N

Atoms of a hydrogen like gas are in a particular excited energy level When these atoms de excite they emit photons of different energies Maximum and minimum energies of emitted photons are Emax 52 224 eV and Emin 1 224 eV respectively Calculate principal quantum number of initially excited energy level lonisation energy of hydrogen atom is 13 6 ev 1 6 2 4 3 5

In a hypothetical atom a negatively charged particle having a charge of magnitude 3e and mass 3m revolves around a proton Here e is the electronic charge and m is the electronic mass Mass of proton may be assumed to be much larger than that of the negatively charged particle thus the proton is at rest This atom obeys Bohr s It is given that for postulate of quantization of angular momentum that is mvr n To B Radius of hypothetical atom is h the first Bohr orbit of hydrogen atom radius of orbit is r speed of electron is total energy is En A speed of the revolving particle in the hypothetical atom is 9v in the first Bohr orbit 2 To D Radius of hypothetical atom is 27 Vo and 9 C Speed of the revolving particle in the hypothetical atom is 3v in the first Bohr orbit

19 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 is are not physically possible 1 3 4 3 1 4 1 2 3 4 2 2 3 4 4 only

The binding energies of the atom of elements A B are Ea Eb respectively Three atoms of the element B fuse to give one atom of element A This fusion process is accompanied by release of energy e Then Ea Eb are related to each other as Question Type Single Correct Type 1 Ea e 3Eb 2 Ea 3Eb 3 Ea e 3E

The ratio of kinetic energy of an electron and the energy of a photon both having the same wavelength is 1 Proportional to the wavelength of the photon 2 Proportional to the energy of the photon 3 Proportional to the kinetic energy of the electron 4 Proportional to the magnitude of velocity of the electron

hat instant getting d e 1 nother stable lly only X is of X and Y is 31 At t 0 light of intensity 10 2 photons s m of energy 6eV per photon starts falling on a plate with work function 2 5 eV If area of the plate is 2x10 4 m and for every 105 photons one charge on the plate at photoelectron is emitted t 25s is a 8 10 15 C c 12 10 0 C b 4x10 14 C d 16x10 2 C

21 A 100 eV electron collides with a stationary helium ion He in its ground state and exits to a higher level After the collision He ions emits two photons in succession with wavelength 1085 and 304 The energy of the electron after the collision will be eV Given h 6 63 x 10 Js 34

A nucleus with mass number A 220 decays by a emission The energy released is 5 5 MeV a good estimate for the kinetic energy of the x particle will be A 4 4 MeV C 5 6 MeV B 5 4 MeV D 6 5 MeV 2003

An electron moves in a circular orbit with a uniform speed v It produces a magnetic field B at the centre of the circle The radius of the circle is proportional to 2005 B v B v VIB X R

Example 14 10 For the damped oscillator shown in Fig 14 20 the mass mof the block is 200 g k 90 N m and the damping constant b is 40 g s Calculate a the period of oscillation b time taken for its amplitude of vibrations to drop to half of its initial value and c the time taken for its mechanical energy to drop to half its Initial value

Find the magnetic moment of an electron of charge e and mass m moving in a Bohr D orbit of radius 2 044 in an Hydrogen atom

E C B i A A DE M The above is a plot of binding energy per nucleon Eb against the nuclear mass M A B C D E F correspond to different nuclei Consider four reactions B C E ii C A B B iii D E F iv F D E where e is the energy released In which reactions is positive 1 F Question Type Single Correct Type i and iv

SolveLancer Test What percent of velocity would be required to be gained lost by an electron present in 2nd orbit in an atom of hydrogen to excite the electron to the 10th orbit SolveLancer Test a 50 b 10 c 80 d None of these O a O b

175 The Schrodinger wave equation for hydrogen atom is 3 2 Y radial 1 Z 16 4 ao 2Zr where ao and Z are the constant in which answer can be expressed and o ao minimum and maximum position of radial nodes from nucleus are respectively ao 3a0 ao 4a0 ao 3a0 2Z Z Z Z 2Z Z a 2 b ao ao 2Z Z 0 1 0 80 12 e 2 c d

2 An electron mass 9 1x10 kg is sent into an electric field of intensity 9 1x10 newton coulomb The acceleration produced is 1 1 6 10 8 m 22 3 1 6x10 m 1 6 10 m 4 1 6 10 m

The frequencies for series limit of Balmer and Paschen series respectively are v and v If frequency of first line of Balmer series is v then the relation between v V and va is A V V V3 B V V3 V2 C V V V3 D V V3 2V

In Bohr s theory for hydrogen like atoms For the higher atomic number radius of the nth orbit is higher O For the higher quantum number velocity of electron in that orbit is greater O In some hypothetical condition if mass of electron would have been higher then electron velocity in that orbit would have been sar For the higher quantum number time period an electron revolving around nucleus is smaller

Total number of air molecules inclusive of oxygen nitrogen water vapour and other constituents in a room of capacity 25 m at a temperature of 27 and 1 atm pressure is Question Type Single Correct Type 1 6 x 1026 26 1025 36 x 1024

An electron of mass m and a photon have same energy E The ratio of de Broglie wavelengths associated with them is Question Type Single Correct Type 1 2 3 4 1 1 E2 c 2m 1 E 2 2m c 2mE 2 1 1 2m 2

Select the incorrect statement O Zn 2 Cut and Cu have same number of d electrons O 1 Electron having n 4 2 m 0 s values of quantum number is present in one of the five degenerate atomic orbitals 2 For any value of 1 2 2 1 values of m are possible There are 2 unpaired electrons in Mn 5

The energy the magnitude of linear momentum magnitude of angular momentum and orbital radius of an electron in a hydrogen atom corresponding to the quantum number n are E p L and r respectively Then according to Bohr s theory of hydrogen atom match the expressions in list I with statement in list 11 1 Epr 11 III Er IV pr 40 List 1 List II P is independent of n Q is directly proportional to n R is inversely proportional to n S is directly proportional to L

Calculate the ratio between the radius of the radium nucleus and the radius of the oxygen nucleus The atomic mass of the radium nucleus is 4 226 and the atomic mass of the oxygen nucleus is 4 16 a 1 5 b 3 0 c 2 4 d 6 0

Match the statements given in List I with their corresponding possible results in List II List I P If photons of ultraviolet light of energy 12 eV are incident on a metal surface of work function of 3eV then the stopping potential in eV will be The ratio of wavelengths of Ka lines of two elements is Q 85 81 between these elements will be R If 20 gm of a radioactive substance due to radioactive decay reduces to 10gm in 4 minutes then in what time in minutes 80 gm of the same substance will reduce to 20 gm Number of elements having atomic numbers 4 List 11 2 3

er n g 6 Q 15 An electron in H atom makes a transition from n 3 to n 1 The recoil momentum of H atom will be 1 6 45 x 10 27 Ns 3 6 45 x 10 24 Ns 2 6 8 x 10 27 Ns 4 6 8 x 10 24 Ns

Which of the following may be an incorrect statement regarding cathode ray discharge tube O Presence of negative charge in cathode rays The magnetic field deflects these rays OIt needs high voltage Protons are present in cathode rays

19 A metal plate weighing 750 g is to be electroplated with 0 05 of its weight of silver If a current of 0 8 A is used find the time approx needed for depositing the required weight of silver ECE of silver is 11 8 x 10 7 kgC CG PMT 2015 a 5 min 32 s c 4 min 16 s b 6 min 37 s d 6 min 10 s

A hydrogen atom in its ground state is irradiated by light of wavelength 970 A Taking hc e 1 237 x 10 eVm and the ground state energy of hydrogen atom as 13 6 eV the number of lines present in the emission spectrum is

The allowed energy levels of electrons in a Hydrogen atom are given by E 13 6 n eV F electronic transition in Hydrogen atom what is the maximum frequency of the emitted photo h 6 62 x 10 34 Js e 1 6 x 10 19 C A 2 1 x 10 GHz B 5 5 x 10 GHz C 3 3 x 10 GHz D 1 7 x 10 GHz

An excited free hydrogen at rest undergoes transition from n 3 to n 1 emitting photon of wavelength then In above question of photon is emitted opposite to direction of motion of wavelength of photon is 1 103 nm 3 103 nm 2 103 nm 4 None of these

4 None of these An element have two isotopes having m and m The relative abundances on isotopes are x and 100 x The a mass of element will be 2 m 100 x m x 100 mx m 100 x 100 3 m m x 100 4 None of these

b A system has four non degenerate single particle energy states 0 E 2E and 3E The system has four particles with total energy 6E List the possible configurations of the particles and their degeneracies if the particles are i distinguishable ii indistinguishable bosons and iii indistinguishable fermions 3

A gas mixture contain 1 g H and 1 g He if temperature of gas mixture is increased from 0 C to 100 C at isobaric process Then find given heat of gas mixture I 5 3 7 7 5 R 2 cal mol K 1 124 cal 2 327 cal 3 218 cal 4 475 cal

Q1 If 13 6 eV energy is required to separat a hydrogen atom into a proton and electron then the orbital radius of electron in hydrogen a 5 3 x 10 11 m b 4 3 x 10 11 m c 6 3 x 10 11 m d 7 3 10 11 m T

energy of the molecules of one mole of oxygen to that of one mole of hydrogen both kept at 100 C is A 16 1 B 4 1 C 1 1 D 1 4 48 Helium has atomic number Z 2 and mass number A 4 The ratio of the radii of the first Bohr orbit of Het ion to that of Hydrogen is B 4 1 40 A 1 4 Than C 1 2 D 2 1

No 2 To explain the fine structure of the spectrum of hydrogen atom we must consider Finite size of the nucleus The presence of neutrons in the nucleus Spin angular momentum Orbital angular momentum Obe Correct Answer 3 Status unattempted M