When a hydrogen atom is raised from the ground state to an excited state 

1. PE decreases and KE increases 

2. PE increases and KE decreases 

3. both KE PE decrease 

4. absorption spectrum

As per the Bohr model, the minimum energy (in eV) required to remove the electron from the ground state of a double ionised lithium ion (Z = 3) is:

1. 1.51

2. 13.6 

3. 40.8

4. 122.4

The ionisation energy of a hydrogen atom is 13.6 eV. Following Bohr's theory, what is the energy corresponding to a transition between the 3^rd and 4^th orbit?
1. 3.40 eV
2. 1.51 eV
3. 0.85 eV 
4. 0.66 eV

The ratio of the energies of the hydrogen atom in its first to second excited states is

1. $\frac{1}{4}$ 

2. $\frac{4}{9}$

3. $\frac{9}{4}$

4. 4

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

1. $2.18\times {10}^5 m/s$   

2. $2.18\times {10}^6 m/s$

3. $2.18\times {10}^7 m/s$   

4. $2.18\times {10}^8 m/s$

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

The ratio of the longest to shortest wavelengths in Lyman series of hydrogen spectra is 

1. $\frac{25}{9}$

2.$\frac{17}{6}$   

3.  $\frac{9}{5}$ 

4. $\frac{4}{3}$

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

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

In terms of Bohr radius $a_0$, the radius of the second Bohr orbit of a hydrogen atom is given by [1992]

1. 4$a_0$ 

2. 8$a_0$ 

3. $\sqrt{2}$$a_0$     

4. 2$a_0$