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

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

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?

An electron jumps from 5th orbit to 4th orbit of hydrogen atom. Taking the Rydberg constant as  ${10}^7$ per metre. What will be the frequency of radiation emitted

(1) $6.75\times {10}^{12} \mathrm{Hz}$             

(2) $6.75\times {10}^{14} \mathrm{Hz}$

(3) $6.75\times {10}^{13} \mathrm{Hz}$             

(4) None of these

Four lowest energy levels of H-atom are shown in the figure. The number of possible emission lines would be

(1) 3             

(2) 4

(3) 5             

(4) 6

The ratio of the wavelengths for 2 $\to$ 1 transition in ${\mathrm{Li}}^{++}$, ${\mathrm{He}}^{+}$ and H is-

1. 1 : 2 : 3           

2.  1 : 4 : 9

3. 4 : 9 : 36           

4. 3 : 2 : 1

The wavelength of light emitted when an electron jumps from second orbit to first orbits in a hydrogen atom is 
(a) $1.215\times {10}^{-7} \mathrm{m}$         (b) $1.215\times {10}^{-5} \mathrm{m}$
(c) $1.215\times {10}^{-4} \mathrm{m}$          (d) $1.215\times {10}^{-3} \mathrm{m}$

Energy of the electron in nth orbit of hydrogen atom is given by ${\mathrm{E}}_{\mathrm{n}}=-\frac{13.6}{{\mathrm{n}}^2}\mathrm{eV}$. The amount of energy needed to transfer electron from first orbit to third orbit is

(1) 13.6 eV             

(2) 3.4 eV

(3) 12.09 eV           

(4) 1.51 eV

The de-Broglie wavelength of an electron in the first Bohr orbit is 

(1) Equal to one fourth the circumference of the first orbit

(2) Equal to half the circumference of the first orbit

(3) Equal to twice the circumference of the first orbit

(4) Equal to the circumference of the first orbit