Radius of the first orbit of the electron in a hydrogen atom is 0.53 Å. So, the radius of the third orbit will be

(1) 2.12 Å             

(2) 4.77 Å

(3) 1.06 Å             

(4) 1.59 Å

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

(1) Proton         

(2) Nucleus

(3) Neutron     

(4) Electrons

The ratio of minimum to maximum wavelength in Balmer series is 

(1) 5 : 9           

(2) 5 : 36

(3) 1 : 4           

(4) 3 : 4

The first line in the Lyman series has wavelength $\mathrm{\lambda }$. The wavelength of the first line in Balmer series is

(1) $\frac{2}{9}\mathrm{\lambda }$             

(2) $\frac{9}{2}\mathrm{\lambda }$
(3) $\frac{5}{27}\mathrm{\lambda }$           

(4) $\frac{27}{5}\mathrm{\lambda }$

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

In the following transitions, which one has higher frequency

(1) 3 – 2             

(2) 4 – 3

(3) 4 – 2             

(4) 3 – 1

The diagram depicts the paths of four \(\alpha\)-particles with identical energies being scattered simultaneously by the nucleus of an atom. Which of these paths are/is not physically possible?

Which of the following is true for number of spectral lines in going from Lyman series to Pfund series ?

(1) Increases

(2) Decreases

(3) Unchanged

(4) May decreases or increases