For principal quantum number $n = 3$, the possible values of orbital quantum number $‘l’$ are

In the spectrum of hydrogen atom, the ratio of the longest wavelength in Lyman series to thelongest wavelength in the Balmer series is

In an alpha particle scattering experiment distance of closest approach for the $\alpha$ particle is $4.5 \times 10^{-14} \mathrm{~m}$. If target nucleus has atomic number $80$ , then maximum velocity of $\alpha$-particle is . . . . .. $\times 10^5$ $\mathrm{m} / \mathrm{s}$ approximately.

$\left(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \mathrm{SI}\right.$ unit, mass of $\alpha$ particle $=$ $\left.6.72 \times 10^{-27} \mathrm{~kg}\right)$

Energy levels $A, B, C$ of a certain atom correspond to increasing values of energy i.e., $E_A < E_B < E_C$. If ${\lambda _1},{\lambda _2},{\lambda _3}$ are the wavelengths of radiation corresponding to the transition $C$ to $B, B$ to $A$ and $C$ to $A$ respectively, which of the following relation is correct ?

The ratio of the speed of the electrons in the ground state of hydrogen to the speed of  light in vacuum is