Atomic Structure Questions and Answers

2 A electron of mass m when accelerated through a potential difference V has de Broglie wavelength A The de Broglie wavelength associated with a proton of mass M accelerated through the same potential difference will be a m M b M C M m d 2 M m

The ratio between acceleration of the electron in singly ionised helium atom and doubly ionised lithium atom 1 both in ground state is a c 8 27 b d 27 8 Z

62 The velocity of an electron in the second orbit of sodium atom is v The velocity of an electron in its fifth orbit will be a v 5 C V 2 an ain b v 2 d v

3 Hydrogen atom emits blue light when it jumps from n 4 energy level to the n 2 level Which colour of light would the atom emit when it changes from the n 5 level to the n 2 level a Red b Yellow c Green d Violet

21 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 Lit will be Ionisation energy of hydrogen atom is 13 6 eV a 182 51 c 142 25 b 177 17 d 113 74

30 In a hypothetical Bohr hydrogen the mass of the electron is doubled The energy Eo and radius ro of the first orbit will be ao is the Bohr radius a Eo 27 2 eV ro ao 2 b Eo 27 2 eV ro ao c Eo 13 6 eV ro a0 2 d Eo 13 6 eV ro ao Ionisation energy of a hydrogen than that of

hm r 6 In the Bohr s model of a hydrogen atom the centripetal force is furnished by the coulomb attraction between the proton and the electron If a is the radius of the ground state orbit m is the mass e is the charge on electron and E is the permittivity of free space the speed of the electron is a C e am e 4 m b Zero d 48 a m

49 Assuming Bohr s model for Li atom the first excitation energy of ground state of Li atom is 1 10 2 eV 2 91 8 eV 3 13 6 eV 4 3 4 eV ition between the first and the

9 Which is the correct relation between de Broglie wavelength of an electron in the nth Bohr orbit and radius of the orbit R 1 n2 R 2 3 2 R n 4TR n 2 R 35

d 4687 8 If an a particle of mass m charge q and velocity v is incident on a nucleus of charge Q and mass m then the distance of closest approach is Qq b 2 mv a C Qq 4 m Qq mv 2 d Qg 2 my

If energy required to remove one of the two electrons from He atom is 29 5 eV then what is the value of energy required to convert a helium atom into particle 1 54 4 eV 3 29 5 eV In Rutherford s experiment 2 83 9 eV 4 24 9 eV

Let F be the frequency of second line of Lyman series and F be the frequency of first line of Balmer series then frequency of first line of Lyman series is given by 2 1 F F 3 F F 2 F F F F

In a hydrogen atom electron moves from second excited state to first excited state and then from first excited state to ground state The ratio of wavelengths is A 20 3 B 15 4 C 27 5 D 5 1

The ionisation potential of hydrogen atom is 13 6V Draw the energy level diagram showing four levels Calculate i the energy of the photon emitted when an electron falls from the third orbit to the second orbit ii the wavelength of this photon value of h and c as above what will be the minimum energy of a photon which can be absorbed by hydrogen atom at ordinary temperature

As the n number of orbit increases the difference of energy between the consecutive energy levels 1 Remains the same 2 Increases 3 Decreases 4 Sometimes increases and sometimes decreases

In which transition of a hydrogen atom photons of lowest frequency are emitted 1 n 4 to n 3 2 n 4 to n 2 3 n 2 to n 1 The speed of an electron in the 4th orbit of hydrogen atom is 4 n 3 to n 1 2

The wavelength of maximum energy released during an atomic explosion was 2 93 x 10 10 m Given that Wein s constant is 2 93 x 10 3 m K the maximum temperature attained must be of the order of 10 7 K 107 K 10 13 K 5 86 107 K

An electron in a hydrogen atom makes a transition from first excited state to ground state The equivalent current due to circulating electron A increases 2 times C increases 8 times B increases 4 times D remains the same

Which of the following combinations should be selected for better tuning of an L C R circuit used for communication NEET Phase 2 2016 1 R 20 22 L 1 5 H C 35 F 2 R 25 2 L 2 5 H C 45 F 3 R 15 92 L 3 5 H C 30 F 4 R 25 22 L 1 5 H C 45 F 008 1

Define the distance of closest approach An a particle of kinetic energy K is bombarded on a thin gold foil The distance of the closest approach is r What will be the distance of closest approach for an a particle of double the kinetic energy n Write 1

Which of the following statements is wrong 1 De Broglie waves are probability waves 2 De Broglie wavelength of a moving particle is inversely proportional to its momentum 3 Wave nature is associated with atomic particles only 4 In general wave nature of matter is not observed

18 Fill in the blanks a b c and d by observing the characters given in the table and choose the correct answer from the following options Fertilisation Vascular tissue Absent Plant group Bryophyta Pterido phyta Gymno sperm Main body Gameto phyte a Sporo phyte By Zoido gamy By Zoido b gamy By Siphono present gamy and Female sex organ c Arche gonium d Zoidogamy a b c 1 Sporophyte Present Archegonium 2 Sporophyte Absent Oogonium 3 Gametophyte Present Oogonium Carpel 4 Gametophyte Present Archegonium Carpel d Archegonium Archegonium

If m is mass of electron v its velocity r the radius of stationary circular orbit around a nucleus with charge Ze then from Bohr s first postulate the speed u of the electron in CGS system in the orbit is equal to Question Type Single Correct Type 1 2 mr V Ze Ze2 mr

The binding energy of deuteron H is 1 112 MeV per nucleon and an a particle H has a binding energy of 7 047 MeV per nucleon Then in the fusion reaction H H He Q the energy Q released is Question Type Single Correct Type 11 MeV 2 11 9 MeV 3 23 8 MeV

Figure shows the results of an experiment involving photoelectric effect The graphs A B C D are related to the light beams having different wavelength Choose incorrect option Current I Retarding 1 Question Type Single Correct Type Beam B has highest frequency Potential V 13 e 3 Beam A has the highest rate of photoelectric emission D Accelerating 2 Photoelectrons ejected by beam B have momentum greater than C and less than A

When an electron in hydrogen atom is excited from its 4th to 5th stationary orbit the change in angular momentum of electron is Question Type Single Correct Type 1 4 6 x 10 34 J S 2 3 32 x 10 34 J s 3 1 05 10 34 J s

According to the Bohr s atomic model the relation between principal quantum number n and radius of orbit r is Your Answer Arxn B rx C I X 1 n 1 n D rxn Correct Answer Feedback

8 In hydrogen and hydrogen like atoms the ratio of difference of energies E4n E2n and E2n En varies with atomic number Z and principal quantum number n as Z a c CNIC b Z4 4 n d None of these a

25 In a hydrogen atom the electron is in nth excited state It comes down to first excited state by emitting ten different wavelengths The value of n is a 6 c 8 b 7 d 9

4 Which of the following combinations should be selected for better tuning of an L C R circuit used for communication NEET Phase 2 2016 1 R 20 22 L 1 5 H C 35 F 2 R 25 92 L 2 5 H C 45 F 3 R 15 Q2 L 3 5 H C 30 F 350 1 5 H C 45 F C

36 The count rate of a radioactive sample falls from 4 0 x 10 s to 1 0 x 10 s in 20 hours What will be the count rate after 100 hours from begining a 3 91 x 10 s c 3 91 x 10 s b 3 91 x 10 s d 3 91 x 10 s 37 Carbon dating is best suited for determining the age of fossils if their age in years is of the order of a 10 b 10 c 10 d 10 3 8

Objective NCERT Phys 73 In accordance with the Bohr s model the quantum number that characterises the earthis revolution around the sun in an orbit of radus 1 5 x 10 m with orbital speed 3 x 10 m s Mass of earth 6 x 10 kg a 5 98 x 106 c 8 57 x 106 b 2 57 x 10 d 2 57 x 10 4 If speed of electron in ground state ener 2 2 x 10 ms then its

Calculate the ratio of the population numbers N1 N2 for the two energy levels E2 and E1 when the material is at room temperature 400K and the difference between the energy levels is 0 35 eV What is the wavelength A of a photon which will be emitted in the transition from E2 to E1

10 3 A hydrogen atom contains one proton and one electron It may be assumed that the electron revolves in a circle of radius 0 53 angstrom 1 angstrom 10 m and is abbreviated as with the proton at the centre The hydrogen atom is said to be in the ground state in this case Find the magnitude of the electric force between the proton and the electron of a hydrogen atom in its ground state 9 Find the speed of the electron in the ground state of a hydrogen atom The description of ground state is given in the previous problem

The potential energy of particle of mass m varies as E for OSIS1 U x 0 for x 1 The de Broglie wavelength of the particle in the range 0 sxs1 is A and that in the range x 1 is A If the total energy of the particle is 2E find a b 3 c d Letim

Two isotopes of a certain element have binding energies that differ by 5 03 MeV The isotope with the larger binding energy contains one more neutron than the other isotope Find the difference in atomic mass between the two isotopes Type your answer here

1 The total energy of an electron in an atom in an orbit is 3 4 eV Its kinetic and potential Henergies are respectively 1 3 4 eV 3 4 eV 2 3 4 eV 6 8 eV 3 3 4 eV 6 8 eV 4 3 4 eV 3 4 eV V V 46

8 eV 1 2 eV 3 0 eV 4 1 eV The ratio of frequencies of incident photons in V2 the graph shown will be Kay 7 eV 4 3 2 1 0 1 5 eV 6 eV 12 1 1 3 11 V 2 4 eV 2 V V2 13 14 3 v Hz 14 13 4 13 12 175

For the given common emitter amplifier circuit Vin applied is 10 V and VBE 0 If VCE is 6 V then value of base current B and collector current Ic are respectively 10 V 10 V 400 KQ 25 A 2 A 2 KQ 25 mA 2 mA 25 A 2 mA

The following reaction occurs in acidic aqueous solution H3 AsO4 Zn AsH3 Zn H3 AsO4 is a number O O of As is O C Reducing 5 O Oxidizing 5 O Reducing 3 Oxidizing 3 agent in which the oxidation

The average and RMS value of voltage for square wave shown in figure 5 254 having peak value are 0 4 V 12 T 2 2V0 T 3 2 Figure 5 254 T 2T B 2V 2

d 4 1 A moving hydrogen atom makes a head on collision with a stationary hydrogen atom Before collision both atoms are in ground state and after collision they move together The minimum value of the kinetic energy of the moving hydrogen atom such that one of the atoms reaches of the excitation state is one a 20 4 eV c 54 4 eV b 10 2 eV d 13 6 eV

B Three concentric spherical shells have radii a b and c a b c and have surface charge densities and o respectively IfVA VB and V denote the potentials of the three shells then for c a b we have AIPMT 2009 o VB VA 4 V V V 1 Vc VB VA 2 Vc 3 V V V

a For what kinetic energy of a neutron will the associated de Broglie wavelength be 1 40x 10 0 m b Also find the de Broglie wavelength of a neutron in thermal equilibrium with matter having an average kinetic energy of 3 kT at 300 K 2

39 An electron and a photon possess the same de Broglie wavelength If E and E respectively are the energies of electron and photon and v and care E their respective velocities then C b 2c c 3c Ep is equal to d V 4c

3 The excitation energy of a hydrogen like ion to its first excited state is 40 8 eV The energy needed to remove the electron from the ion in the ground state is a 54 4 eV c 72 6 eV b 62 6 eV d 58 6 eV from finat oxcited state to ground state The

the correct statement 1 A particle at rest breaks into two particles of different masses They fly off in different directions Their de Broglie wavelength will be different 2 Density of nucleus depends upon the mass number 3 Radius of nucleus is independent of mass number 4 In exothermic fission reaction binding energy per nucleon of product nuclei is more than

A particle of mass m moves in a circular orbit in a centra potential field U r kr If Bohr s quantization conditions 1 kr 2 2 are applied radii of possible orbitals and energy levels vary with quantum number n as Main 2019 12 Jan I 1 a rn Enn c n E n n b m n En d r n En x X n 2 1 n

24 A point source of electromagnetic an average power output of The maximum value of electric field at a distance 3 5 m from source will be 1 12 V m 3 31 3 V m 2 40 E 4 62 6 radiation has 800 W m

Quiz Bot Quize conductor 1 15 Certain substance emits only the wavelengths A1 A2 A3and 4 when it is at a high temp When this substance is at a colder temp it will absorb only the foll wavelengths a 1 b 2 c A1 A2 d A1 A2 A3 14 Final Results 0 C