For $Li^{2+}$ ion,the ratio of radii $r_2 : r_5$ will be

The limiting line in the Balmer series of the $H$ spectrum has a frequency of ....... $(R_\infty = 3.29 \times 10^{15} \, cycles/s)$

Find the radius of the first,second,and third orbits of the hydrogen atom.

When $\alpha$-particles are sent through a thin metal foil,most of them go straight through the foil because

What transition in $He^{+}$ ion shall have the same wave number as the first line in Balmer series of hydrogen atom?

The wavenumber of the first spectral line of the Lyman series of $He^{+}$ ion is $x \ m^{-1}$. What is the wavenumber (in $m^{-1}$) of the second spectral line of the Balmer series of $Li^{2+}$ ion?