If the energy of a hydrogen atom in nth orbit is ${\mathrm{E}}_{\mathrm{n}}$, then energy in the nth orbit of a singly ionized helium atom will be 

(1) 4${\mathrm{E}}_{\mathrm{n}}$             

(2) ${\mathrm{E}}_{\mathrm{n}}$/4

(3) 2${\mathrm{E}}_{\mathrm{n}}$             

(4) ${\mathrm{E}}_{\mathrm{n}}$/2

The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state

1. 0 eV                       

2. – 27.2 eV

3. 1 eV                       

4. 2 eV

As the electron in Bohr orbit of Hydrogen atom passes from state n = 2 to n = 1 , the kinetic energy K and potential energy U change as 

(1) K two-fold, U four-fold

(2) K four-fold, U two-fold

(3) K four-fold, U also four-fold

(4) K two-fold, U also two-fold

The magnetic moment $\left(\mathrm{\mu }\right)$ of a revolving electron around the nucleus varies with principal quantum number n as

(1) $\mathrm{\mu }\propto \mathrm{n}$            

(2) $\mathrm{\mu }\propto 1/\mathrm{n}$

(3) $\mathrm{\mu }\propto {\mathrm{n}}^2$           

(4) $\mathrm{\mu }\propto 1/{\mathrm{n}}^2$

Bohr's atom model assumes 

(1) The nucleus is of infinite mass and is at rest

(2) Electrons in a quantized orbit will not radiate energy

(3) Mass of electron remains constant

(4) All the above conditions

The ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is

1. 1/2                2. 2/137
3. 1/137            4. 1/237

A double charged lithium atom is equivalent to hydrogen whose atomic number is 3. The wavelength of required radiation for exciting electron from first to third Bohr orbit in ${\mathrm{Li}}^{++}$ will be (Ionisation energy of hydrogen atom is 13.6eV) 
(a) 182.51 Å                 (b) 177.17 Å
(c) 142.25 Å                 (d) 113.74 Å

The ionisation potential of H-atom is  13.6 V. When it is excited from ground state by monochromatic radiations of $970.6 \stackrel{0}{\mathrm{A}}$, the number of emission lines will be (according to Bohr’s theory) 
(1) 10           

(2) 8

(3) 6             

(4) 4

Imagine an atom made up of a proton and a hypothetical particle of double the mass of the electron but having the same charge as the electron. Apply the Bohr atom model and consider all possible transitions of this hypothetical particle to the first excited level. The longest wavelength photon that will be emitted has wavelength $\mathrm{\lambda }$ (given in terms of the Rydberg constant R for the hydrogen atom) equal to

(1) 9/(5R)                 
(2) 36/(5R)
(3) 18/(5R)               
(4) 4/R