In Bohr’s model, if the atomic radius of the first orbit is ${\mathrm{r}}_0$, then the radius of the fourth orbit is 
(1) ${\mathrm{r}}_0$             

(2) 4${\mathrm{r}}_0$

(3)${\mathrm{r}}_0$/16         

(4) 16${\mathrm{r}}_0$

If R is the Rydberg’s constant for hydrogen the wave number of the first line in the Lyman series will be

(1) $\frac{\mathrm{R}}{4}$                   

(2) $\frac{3\mathrm{R}}{4}$
(3) $\frac{\mathrm{R}}{2}$                 

(4) 2R

In hydrogen atom, if the difference in the energy of the electron in n =2 and n = 3 orbits is E, the ionization energy of hydrogen atom is 

(1) 13.2 E               

(2) 7.2 E

(3) 5.6 E                 

(4) 3.2 E

The first member of the Paschen series in hydrogen spectrum is of wavelength 18,800 Å. The short wavelengths limit of Paschen series is 

(1) 1215 Å     

(2) 6560 Å

(3) 8225 Å     

(4) 12850 Å

In Bohr model of hydrogen atom, the ratio of periods of revolution of an electron in n =2 and n = 1 orbits is

(1) 2 : 1             

(2) 4 : 1

(3) 8 : 1             

(4) 16 : 1

The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true 

The ratio of minimum to maximum wavelength in Balmer series is 

(1) 5 : 9           

(2) 5 : 36

(3) 1 : 4           

(4) 3 : 4

Rutherford’s $\mathrm{\alpha }$-particle experiment showed that the atoms have

(1) Proton         

(2) Nucleus

(3) Neutron     

(4) Electrons