According to Bohr's theory,the angular momentum of an electron in the $5^{th}$ orbit is: (in $, h/\pi$)

Which of the following statements regarding the $H$ atom spectrum is correct?

$A$ photon of wavelength $3000 \ \mathring{A}$ strikes a metal surface. The work function of the metal is $2.13 \ eV$. What is the kinetic energy of the emitted photoelectron (in $eV$)? $\left(h=6.626 \times 10^{-34} \ J \ s\right)$

State whether the following statements are true or false:
$(i)$ When an electron in a hydrogen atom returns from the third excited state to the ground state,it emits frequencies corresponding to lines in the Lyman,Balmer,and Paschen series.
$(ii)$ When an electron in a hydrogen atom returns from the third excited state to the ground state,it emits radiation with wavelengths corresponding to the Pfund series,which has very high frequencies.

The angular momentum of an electron in a given orbit is $J$. Its kinetic energy will be:

Time taken for an electron to complete one revolution in the Bohr orbit of hydrogen atom is