Question

if the radius of first bohr orbit of hydrogen atom is equal to the radius of second bohr orbit of a hydrogenic species, then the number of protons in the nucleus of hydrogenic species are

Answer 1

First bohr orbit of hydrogen = second bohr orbit of hydrogenic species

$$\begin{gathered} Bohrradius=\frac{n^2{a}_0}{Z} \\ Forhydrogenr=a_{0}inthefirstorbit \\ Forhydrogenicspeciesinthesecondorbitn=2 \\ r=\frac{2^2{a}_0}{Z} \\ Asradiusofhydrogenfirstorbit=hydrogenicsecondorbit \\ Z=4 \\ Thatmeansithas4protons \end{gathered}$$