The radius of the first permitted Bohr orbit for the electron in a hydrogen atom equals \(0.5~\mathring{{A}}\) and its ground state energy equals \(-13.6~\text{eV}.\) If the electron in the hydrogen atom is replaced by a muon \((\mu^{-})\)$$[charge same as electron and mass \(207~m_e\)${}_{}$], the first Bohr radius and ground state energy will be:
( \(m_e\) represents the mass of an electron)

1.	\(0.53\times10^{-13}~\text{m}, ~-3.6~\text{eV}\)
2.	\(25.6\times10^{-13}~\text{m}, ~-2.8~\text{eV}\)
3.	\(2.56\times10^{-13}~\text{m}, ~-2.8~\text{keV}\)
4.	\(2.56\times10^{-13}~\text{m}, ~-13.6~\text{eV}\)

An electron in Bohr's hydrogen atom has angular momentum $\frac{2h}{\mathrm{\pi }}$. The energy of the electron is 

1.  -3.4 eV

2.  -0.64 eV

3.  -0.85 eV

4.  -10.25 eV

If the energy of the electron in an \(\mathrm{H}\)-atom in the ground state is taken to be \(-13.6\) eV, then the kinetic energy of the electron in the first excited state will be:
1. \(3.4\) eV
2. \(6.8\) eV
3. \(10.2\) eV
4. \(13.6\) eV

An electron and a proton are separated by a large distance. The electron starts approaching the proton with energy 2eV. The proton captures the electron and forms a hydrogen atom in first excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4600Å. The maximum K.E. of the emitted photoelectron is (Take hc = 12420 eV Å)

1. 2.4 eV                     

2. 2.7 eV                     

3. 2.9 eV                         

4. 5.4 eV

The radius of Germanium \((\mathrm{Ge})\) nuclide is measured to be twice the radius of \({}_{4}^{9}\mathrm{Be}.\) The number of nucleons in \(\mathrm{Ge}\) is:
1. \(73\)
2. \(74\)
3. \(75\)
4. \(72\)

In a discharge tube ionization of enclosed gas is produced due to collisions between:

1. positive ions and neutral atoms/molecules

2. negative electrons and neutral atoms/molecules

3. photons and neutral atoms/molecules

4. neutral gas atoms/molecules