NEET Chemistry — Structure of Atom

What is the maximum number of electrons that can occupy the subshell with principal quantum number $n = 2$ and azimuthal quantum number $l = 1$?

A photon of wavelength $200 \, \text{nm}$ ejects an electron from a metal with a velocity of $6.62 \times 10^5 \, \text{m s}^{-1}$. What is the work function of the metal? ($h = 6.626 \times 10^{-34} \, \text{J s}$, $c = 3.0 \times 10^8 \, \text{m s}^{-1}$, $m_e = 9.1 \times 10^{-31} \, \text{kg}$)

The number of spectral lines produced when an electron in a hydrogen atom falls from $n = 5$ to $n = 2$ is:

What is the wavelength of the second line in the Balmer series of a hydrogen atom? ($R_H = 1.097 \times 10^7 \, \text{m}^{-1}$)

The velocity of an electron in the second orbit of a hydrogen atom is $1.095 \times 10^6 \, \text{m s}^{-1}$. What is its de Broglie wavelength in this orbit? ($h = 6.626 \times 10^{-34} \, \text{J s}$, $m_e = 9.1 \times 10^{-31} \, \text{kg}$)