When electron jumps from n = 4 to n = 2 orbit, we get [2000]

1. second line of Lyman series

2. second line of Balmer series

3. second line of Paschen series

4. an absorption line of Balmer series

Hydrogen atoms are excited from ground state of the principal quantum number 4. Then, the number of spectral lines observed will be

1. 3   

2. 6

3. 5

4. 2

Energy levels A, B, C of a certain atom correspond to increasing values of energy i.e. $E_A<E_B<E_C.$ If ${\lambda }_1,<mspace\; width="1em"></mspace>{\lambda }_2,<mspace\; width="1em"></mspace>{\lambda }_3$ are the wavelengths of the radiation corresponding to the transitions C to B, B to A and C to A respectively, which of the following relation is correct?

1. ${\lambda }_3={\lambda }_1+{\lambda }_2$ 

2. ${\lambda }_3=\frac{{\lambda }_1{\lambda }_2}{{\lambda }_1+{\lambda }_2}$

3. ${\lambda }_1+{\lambda }_2+{\lambda }_3=0$ 

4. ${\lambda }_3^2={\lambda }_1^2+{\lambda }_2^2$

The velocity of the electron in the ground state (H - atom) is 

1. $2.18\times {10}^5<mspace\; width="1em"></mspace>m/s$   

2. $2.18\times {10}^6<mspace\; width="1em"></mspace>m/s$

3. $2.18\times {10}^7<mspace\; width="1em"></mspace>m/s$   

4. $2.18\times {10}^8<mspace\; width="1em"></mspace>m/s$

In the Rutherford scattering experiment, what will be the correct angle for $\propto$-scattering for an impact parameter, b = 0?

1. ${90}^{\circ }$

2. ${270}^{\circ }$

3. $0^{\circ }$ 

4. ${180}^{\circ }$

Which of the following transitions gives photon of maximum energy?

1. n = 1 to n = 2 

2. n = 2 to n = 1

3. n = 2 to n = 6 

4. n = 6 to n = 2

Calculate the highest frequency of the emitted photon in the Paschen series of spectral lines of the Hydrogen atom:

1. $3.7\times {10}^{14}<mspace\; width="1em"></mspace>Hz$ 

2. $9.1\times {10}^{15}<mspace\; width="1em"></mspace>Hz$

3. $10.23\times {10}^{14}<mspace\; width="1em"></mspace>Hz$

4. $29.7\times {10}^{15}<mspace\; width="1em"></mspace>Hz$

The element which has K$\alpha$ X-ray line whose wavelength is 0.18 nm is:

1. Cobalt 

2.  Xenon

3. Copper 

4. Iron