The Rutherford $\mathrm{\alpha }$-particle experiment shows that most of the $\mathrm{\alpha }$-particles pass through almost unscattered while some are scattered through large angles. What information does it give about the structure of the atom?

1.	Atom is hollow.
2.	The whole mass of the atom is concentrated in a small center called the nucleus.
3.	Nucleus is positively charged.
4.	All of the above

An electron has a mass of $9.1\times {10}^{-31} \mathrm{kg}$. It revolves round the nucleus in a circular orbit of radius $0.529\times {10}^{-10}$ metre at a speed of $2.2\times {10}^6 \mathrm{m}/\mathrm{s}$. The magnitude of its linear momentum in this motion is

(a) $1.1\times {10}^{-34 }$kg-m/s             (b) $2.0\times {10}^{-24}$ kg-m/s 
(c) $4.0\times {10}^{-24}$ kg-m/s           (d) $4.0\times {10}^{-31}$ kg-m/s

An electron jumps from the 4th orbit to the 2nd orbit of hydrogen atom. Given the Rydberg's constant R = ${10}^5 {\mathrm{cm}}^{-1}$. The frequency in Hz of the emitted radiation will be 
(a) $\frac{3}{16}\times {10}^5$           (b) $\frac{3}{16}\times {10}^{15}$
(c) $\frac{9}{16}\times {10}^{15}$          (d) $\frac{3}{4}\times {10}^{15}$

An electron in the n = 1 orbit of hydrogen atom is bound by 13.6 eV. If a hydrogen atom is in the n = 3 state, how much energy is required to ionize it 
(1) 13.6 eV                     

(2) 4.53 eV
(3) 3.4 eV                       

(4) 1.51 eV

Which of the following statements about the Bohr model of the hydrogen atom is false 

(1) Acceleration of electron in n = 2 orbit is less than that in n = 1 orbit

(2) Angular momentum of electron in n = 2 orbit is more than that in n = 1 orbit

(3) Kinetic energy of electron in n = 2 orbit is less than that in n = 1 orbit

(4) Potential energy of electron in n = 2 orbit is less than that in n = 1 orbit

Ratio of the wavelengths of first line of Lyman series and first line of Balmer series is

(1) 1: 3                 

(2) 27 : 5

(3) 5 : 27               

(4) 4 : 9

In Bohr's model, the atomic radius of the first orbit is ${\mathrm{r}}_0$, then the radius of the third orbit is
(1) $\frac{{\mathrm{r}}_0}{9}$              

(2) ${\mathrm{r}}_0$
(3) $9{\mathrm{r}}_0$               

(4) $3{\mathrm{r}}_0$

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