The total number of spectral lines observed when an electron returns from the $6^{th}$ shell to the $2^{nd}$ shell in a hydrogen atom is:

In the hydrogen spectrum,if an electron transitions from the $6^{th}$ orbit to the $3^{rd}$ orbit,what is the total number of spectral lines in the visible region?

Which one of the following corresponds to the wavelength of a line in the Balmer series of the $H$ atom spectrum? $(R =$ Rydberg constant$)$

Which of the following is correct for any $H^-$-like species?

The energy of the first (lowest) Balmer line of the $H$ atom is $x \ J$. The energy (in $J$) of the second Balmer line of the $H$ atom is:

The angular momentum of the $2^{nd}$ Bohr orbit of the $H$ atom is $x$. Find the angular momentum of the $1^{st}$ excited state of $Li^{+2}$.