The frequency of the first line of the Paschen series in the spectrum of the $Be^{+3}$ ion is:

Light of frequency $1.6 \times 10^{16} \ Hz$ falling on a metal plate emits electrons that have double the kinetic energy compared to the kinetic energy of electrons emitted when light of frequency $1.0 \times 10^{16} \ Hz$ falls on the same plate. The threshold frequency $(v_0)$ of the metal in $Hz$ is:

The ratio of the radius of the second orbit of $Li^{2+}$ to that of the third orbit of $Be^{3+}$ is:

Bohr's model can explain:

For the Paschen series, the values of $n_1$ and $n_2$ in the expression $\Delta E = R h c \left( \frac{1}{n_1^2} - \frac{1}{n_2^2} \right)$ are:

The energy required by electrons, present in the first Bohr orbit of hydrogen atom to be excited to the second Bohr orbit is . . . . . . $J \ mol^{-1}$.
Given: $R_{H} = 2.18 \times 10^{-11} \ ergs$