NUCLEUS ,ATOM AND DUAL NATURE OF MATTER

The ratio between Bohr radii is

• (a) 1 : 2 : 3

• (b) 2 : 4 : 6

• (c) 1 : 4 : 9

• (d) 1 : 3 : 5

. The K.E. of the electron in an orbit of radius r in hydrogen atom is proportional to

In terms of Rydberg constant R, the wave number of the first Balmer line is

• (a) R

• (b) 3R

• (c) 5R/36

• (d) 8R/9

The ionisation energy of hydrogen atom is 13.6 eV. Following Bohr’s theory the energy corresponding to a transition between 3rd and 4th orbits is

• (a) 3.40 eV

• (b) 1.51 eV

• (c) 0.85 eV

• (d) 0.66 eV

The transition of electron from n = 4, 5, 6, ………. to n = 3 corresponds to

• (a) Lyman series

• (b) Balmer series

• (c) Paschen series

• (d) Brackettseries

6. Which of the following spectral series in hydrogen atom gives spectral line of 4860 A?

• (a) Lyman

• (b) Balmer

• (c) Paschen

• (d) Brackett

For ionising an excited hydrogen atom, the energy required (in eV) will be

• (a) a little less than 13.6 eV

• (b) 13.6 eV

• (c) more than 13.6 eV

• (d) 3.4 or less

Calculate the wavelength of radiation emitted, when an electron having total energy -1.5 eV makes a transition to the ground state. [Given energy in the ground state = -13.6eV and Rydberg’s constant=1.09 x 107 m-1 )

In Bohr Model, what is the atomic radius of 3rd orbit?

Radii of the permitted orbits increase in …………… ratio.

• a) 1 : 2 : 3

• b) 2: 4 : 6

• c) 1 : 4 : 9

• d) 1: 4 : 6