Atomic Structure Questions and Answers

Before carrying out the test for the presence of starch in a leaf on exposure to sunlight the leaf is put into alcohol in a beaker and boiled over a water bath This step is carried out to a extract starch b dissolve chlorophyll c allow water to move into a leaf d make membranes of leaf cells more permeable

4 The de Broglie wavelength of a neutron corresponding to root mean square speed at 927 C is 2 What will be the de Broglie wavelength of the neutron corresponding to root mean square speed at 27 C a 2 c 22 b a d 42 D

1 The wavelength for n 3 to n 2 transition of the hydrogen atom is 656 3 nm What are the wavelengths for this same transition in a positronium which consists of an electron and a positron b singly ionized helium Note A positron is a positively charged electron

d E p lc 6 Which of o a E p c b E 7 Two photons having a equal wavelengths have equal linear momenta b equal energies have equal linear momenta c equal frequencies have equal linear momenta her of photons of wavelength 540 nm emitted d All of the above ower 100 W Accor given Fron

Hydrogen atom in ground state is excited by a monochromatic radiation of 975 A Number of spectral lines in the resulting spectrum emitted will be AIPMT 2014 1 3 3 6 2 2 4 10 state emitte work the ph 1 5

In the Bohr model of H atom an electron e is revolving around a proton p with velocity v if r is the radius of orbit and m is mass of electron and Eo is permittivity of vacuum the value of kinetic energy of electron is e 4T Eor e 8T Eor 4Te Eor 4 Eor

covalent bonds due to the high electric field 6 A change of 8 0 mA in the emitter current brings a change of 7 9 mA in the collector current The values for a and B will be 1 0 9875 79 3 0 95 19 2 0 99 99 4 0 98 49

wavelength 26 The longest wavelength of the Lyman series for hydrogen atom is the same as the of a certain line in the spectrum of He when the electron makes a transition from n 2 The value of n is a 3 2h c 2 V V b 4 c 5 d 6 in 7 92 R 1 0973 x107m 1

1 Which of the following curves may represent the speed of the electron in a hydrogen atom as a function of the principal quantum number n

a 2 C b 3 2 x 10 5 A sample of sodium has a mass of 46 g What is the mass of the same number of calcium atoms as sodium atoms present in given sample a 46 g b 20 g d 80 g c 40 g of noutrons present in 54 mL H O 1 are d none of these

Electron in a hydrogen atom first jumps from fifth excited state to third excited state and then from third excited state to second excited state The ratio of wavelengths emitted in two cases is 1 3 25 16 5 4 2 4 7 5 125 64

A particle known as u meson has a charge equal to that of an electron and mass 208 times the mass of the electron It moves in a circular orbit around a nucleus of charge 3 e Take the mass of the nucleus to be infinite Assuming that the Bohr s model is applicable to this system a derive an expression for the radius of the nth Bohr orbit b find the value of n for which the radius of the orbit is approximately the same as that of

1992 1991 The Bohr radius of the fifth electron of phosphorous atom atomic number 15 acting as a dopant in silicon relative dielectric constant 12 is The w

If the attractive potential between electron and proton were given by V r Vo In 5 To B n D 1 n where V To are constants the radius rn of the nth Bohr orbit in Hydrogen atom would be proportional to 2 A n C 1 n 20

The energy of ground electronic state of hydrogen atom is 13 6 eV The energy of the first excited state will be a 54 4 eV b 27 2 eV 1997 c 6 8 eV d 3 4 eV

Of the following the one which has the de Broglie wavelength for the same speed is a electron c particle b proton d oxygen atom largest 2010

A neutron moving with speed v makes a head on collision with a hydrogen atom in ground state kept at rest Find the minimum kinetic energy of the neutron for which inelastic completely or partially collision may take place The mass of neutron mass of hydrogen 1 67 10 kg 27

A stationary hydrogen atom emits photon corresponding to the first line of Lyman series If R is the Rydberg constant and M is the mass of the atom then the velocity acquired by the atom is 4M b 3Rh 4M Rh a c 3Rh 4M Rh 4M d 81

1 K In case of LED if we increase forward applied voltage intensity of emitted light increases 1 Intensity of emitted light increases 2 Intensity of emitted light decreases 3 Intensity of emitted light first increases then decreases 4 Intensity of emitted light first decreases then increases

Let in energy level of a certain atom frequency v is emitted when the electron makes a transition from energy level of energy 3E to 2E The frequency emitted during transition from energy 3E 2 level of energy 2E to 1 2v 3 is 2 v 4 3v

Marks Questions Determine the de Broglie wavelength of a proton whose kinetic energy is equal to the rest mass energy of an electron Mass of a proton 1836 times that of electron In which region of electromagnetic spectrum does this wavelength lie All India 20110

A uranium 238 nucleus initially at rest emits an a He particle with energy E The recoil speed of residual nucleus thorium 234 is Masses are same as their mass number 1 3 2E 234 2E 117 2 4 E 234 E 117

For which one of the following Bo valid Singly ionised neon atom Ne Hydrogen atom Singly ionised helium atom He 2 3 4 Deuteron atom

The radius of the 4th orbit of the electron will be smaller than its 8th orbit by a factor of A 2 C 8 B 4 D 16

The mass of Li is 0 042 amu less than the sum of masses of its constituents The binding energy per nucleon is

2 13 Fig shows the results of an experiment involving photoelectric effect The graphs A B C D related the light beam having different wavelengths Can C D Accelerating Retarding 0 A Beam B has highest frequency B Beam C has longest wavelength C Beam A has the highest rate of photoelectric emission D Photoelectrons ejected by beam B have the highest momentum

n An electron from various excited states of hydrogen atom emit radiation to come to the ground state Let be the de Broglie wavelength of the electron in the nth state and the ground state respectively Let An be the wavelength of the emitted photon in the transition from the nth state to he ground state For large n A B are onstants JEE Main 2018 R

prehension IV In a hypothetical positronium atom attraction between positron and electron bounds them if sum of magnitude o linear momenta of atomic particle is quantized in the integral steps of boh 27 where bo is a ve constant 1 Energy of atom in nth orbit is proportional to A n C 1 n Energy of atom in ground state will be b h A C 167 m b h 87 m B n D 1 n b h 2 m b h 97 m B D

q For a non relativistic i e v c charged particle specific charge m constant

4 unit photo electric current is flowing the distance between source and cathode is 4 unit Now distance between source and cathode becomes 1 unit What will be photo electric current now The wavelength of photons in two cases are 4000 and 3600 A respectively what is difference in stopping potential for these two Andr 23 Threshold frequency of a surface is v It is illuminated by 3 v frequency then maximum speed of photo electrons is V m sec What will be maximum speed if incident frequency is 9 v When incident wavelength is stopping potential is 3 V If incident wavelength is 22 then stopping potentia is V Find out threshold wavelength in terms of 2 A light beam of power 1 5 mW and 400 nm wavelength incid hen find out obtained photo

A particle of mass M at rest decays into two particles of masses m and m having non zero velocities The ratio of the de Broglie wavelengths of the particles A A2 is a m m b m m1 c 1 0 d m m to riit

An electron in hydrogen atom after absorbing energy photons can jump between energy states n and n n n Then it may return to ground state after emitting six difference wavelengths in emission spectrum The energy of emitted photons is either equal to less than or greater than the absorbed photons Then n and n are A n 4 n 3 B n 5 n 3 C n 4 n 2 D n 5 n 1

5 Which of the following is directly proportional to principal quantum number 1 Linear momentum 2 Kinetic energy 3 Total energy LA Mognatio homont muanh 21 n

When the velocity of a relativistic charged particle increases it s specific charge Decreases 2 Increases 4 First decreases then increases 1 3 Remains same

The transition from the state n 3 to n 1 in a hydrogen like atom results in ultraviolet radiation Infrared radiation will be obtained in the transition from AIPMT Mains 2012 2 3 2 4 4 3 1 2 1 3 5 2

2 V 3 4V 2 N 100 molecules of a gas have velocities 1 2 3 N km s respectively Then 1 rms speed and average speed of molecules are same 2N 1 N 1 2 Ratio of rms speed and average speed is 6N 3 Ratio of rms speed and average speed is 2N 1 N 1 6 4 Ratio of rms speed and average speed of molecules is 2 2N 1 3 N 1 m

5 An electron of mass m with an initial velocity V V i V 0 enters an electric field E E Eo constant 0 at t 0 If o is its de Broglie wavelength initially then its de Broglie wavelength at time t is 1 1 3 Apt 20 eEt mV 2 21 4 30 eE mV

1 The De Broglie wavelength associated with electrons revolving round the nucleus in a hydrogen atom in ground state will be mib E 1 0 3 2 3 3 3 6 62 4 10

Statement 1 When a neutron with energy 10 2eV collides with a hydrogen atom in ground state the electron will be excited to first excited state Statement 2 The collision between atoms can be either elastic inelastic or perfectly inelastic

37 Maximum frequency of emission is obtained for the transition 1 n 2 to n 1 2 n 6 to n 2 3 n 1 to n 2 4 n 2 to n 6

There are two atoms of an element if one takes an electron from another 4eV is needed where as for the process A A 10eV is needed Ionisation potential and electron affinity of A in eV are respectively A 6 4 B 7 3 C 6 5 3 5 D None of these

14 The de Broglie wavelength of a neutron in them equilibrium with heavy water at a temperature Kelvin and mass m is 1 3 H2h 2 leismal 3mkTbb h 3mkTusn narii lejer 2h h 4 TmkT

Who discovered photo electric effect 1 Hertz 2 Lenard 3 Hallwach The energy of a photon is equal to 3 kilo eV Calculate its linear momentum tic light of wave length 500 nm is incident norm

The equivalent weight of H PO in following reaction is H PO Ca OH CaHPO 2H O 1 98 2 49 3 32 66 4 40 0 Which bond angle gives maximum dipole moment for triatomic molecule XY 1 0 90 2 0 120 3 0 180 4 Both 2 and 3

In which of the following cases the heavier of the two particle has a smaller De broglie wavelength A Both move with the same speed B Both move with the same linear momentum C Both move with the same kinetic energy D Both have the same change of potential energy in a conservative field when they start moving from rest

A nucleus with mass number 220 initially at rest emits 30 an a particle If the Q value of the reaction is 5 5 MeV the kinetic energy of the a particle is a 4 4 MeV b 5 4 MeV c 5 6 MeV d 6 5 MeV

The momentum of a photon having energy equal to the rest mass energy of an electron is 1 2 73 x 10 22 kg ms 1 2 1 99 10 24 kg ms 1 3 3 33 x 10 22 kg ms 1 4 2 11 10 22 kg ms 1 The de Broglie wavelength of electron in 4th orbit of hydrogen atom is Radius of the first orbit is ro 3 1 Tro 4 3 4 3 Turo 2 8 r 4 4 ro 42

400 124 Hydrogen atom in the ground state is excited by a monochromatic radiation of 975 Number of spectral lines in the resulting spectrum emitted will be a 3 c 6 R 1 b 2 d 10 AIPMT 2014 1 1 RXX 106

2C s 202 g H 12 0 H O 2CO g AH 787 kJ AH 286 kJ C H g 5 2 O2 g 2CO2 g H O l AH 1301 kJ Heat of formation of acetylene is a 1802 kJ b 1802 kJ c 800 kJ d 228 kJ

8 A transition metal X has a configuration Ar 3d5 in its 3 oxidation state Its atomic number is 1 22 2 26 3 28 4 19