The ionization potential of a hydrogen atom is $13.6 \ eV$. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy $12.1 \ eV$. According to Bohr's theory,the number of spectral lines emitted by the hydrogen atoms will be:

In the Bohr model of the hydrogen atom,the angular velocity $\omega_n$ of the electron depends on the principal quantum number $n$ as:

$A$ hydrogen atom in its ground state absorbs $10.2 \; eV$ of energy. The angular momentum of the electron of the hydrogen atom will increase by the value of ............... $\times 10^{-34} \; J \cdot s$ (Given,Planck's constant $h = 6.6 \times 10^{-34} \; J \cdot s$)

The radius of the orbit of an electron in a $H$-atom changes from $2.12 \mathring{A}$ to $4.77 \mathring{A}$. The $H$-atom has:

Write the quantum condition suggested by Bohr for the angular momentum of the electron.

Apply Bohr's atomic model to a lithium atom. Assuming that its two $K$-shell electrons are so close to the nucleus that the nucleus and the $K$-shell electrons act as a core with an effective positive charge equivalent to $1e$. The ionization energy of its outermost electron is......$eV$.