The ionisation potential of hydrogen atom is

1. 13.60 volt

2. 8.24 volt

3. 10.36 volt 

4. 14.24 bolt

Orbital acceleration of electrons is:
1. $\frac{n^2h^2}{4\pi^2m^2r^3}$
2. $\frac{n^2h^2}{4n^2r^3}$
3. $\frac{4n^2h^2}{\pi^2m^2r^3}$
4. $\frac{4n^2h^2}{4\pi^2m^2r^3}$

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model:

1. 13.6 eV

2. 0.65 eV

3. 1.9 eV

4. 11.1 eV