Atoms

Ratio of longest wavelength corresponding to Lyman and Balmer series in hydrogen spectrum is 

• 5/27

• 3/23

• 7/29

• 7/29

Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de - Broglie wavelength associated with the electrons would

• decrease by 2 times

• decrease by 4 times

• increase by 4 times

• increase by 4 times

The wavelength of the first line of Layman series for the hydrogen atom is equal to that of the second line of Balmer series for a hydrogen-like an ion. The atomic number Z  of hydrogen-like ion is 

• 4

• 1

• 2

• 2

In the spectrum of hydrogen, the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series is 

• 4/9

• 9/4

• 27/5

• 27/5

The energy of a hydrogen atom in the ground state is -13.6 eV. The energy of a He⁺ ion in the first excited state will be

• -13.6 eV

• -27.2 eV

• -54.4eV

• -54.4eV

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be

• 2.4 V

• -1.2 V

• -2.4 V

• -2.4 V

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. If the work functions of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron is nth state E_n = -13.6/n² eV)

• 5.1 V

• 12.1 V

• 17.2 V

• 17.2 V

In a Rutherford scattering experiment when a projectile of charge Z₁ and mass M₁ approaches a target nucleus of charge Z₂ and mass M₂, the distance of closest approach is r_o.The energy of the projectile is 

• directly proportional to M₁ x M₂

• directly proportional to Z₁Z₂

• inversely proportional to Z₁

• inversely proportional to Z₁

The ionisation 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

• n = 3 to n =2 states

• n = 3 to n = 1 states

• n = 2 to n = 1 states

• n = 2 to n = 1 states

The total energy of an electron in the ground state of a hydrogen atom is -13.6 eV. The kinetic energy of an electron in the first excited state is: 

• 3.4 eV

• 6.8 eV

• 13.6 eV

• 13.6 eV