If the electron jumps from $7.00 \ eV$ energy level to $5.0 \ eV$ energy level,it :

In a photoelectric effect experiment, the kinetic energy of an emitted electron is $1.986 \times 10^{-19} \ J$, when a radiation of frequency $1.0 \times 10^{15} \ s^{-1}$ hits the metal. What is the threshold frequency of the metal (in $s^{-1}$)? (Planck's constant $= 6.62 \times 10^{-34} \ J \ s$)

$A$ $50 \, W$ bulb emits monochromatic red light of wavelength $795 \, nm$. The number of photons emitted per second by the bulb is $x \times 10^{20}$. The value of $x$ is $......$.
$[ \text{Given} : h=6.63 \times 10^{-34} \, J \cdot s \text{ and } c=3.0 \times 10^{8} \, m \cdot s^{-1} ]$

In the Balmer series of lines of the hydrogen spectrum,the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen?

Which one of the following transitions of an electron in a hydrogen atom emits radiation of the lowest wavelength?

The ionization potential of hydrogen atom is $13.6 \ eV$. The energy required to remove an electron from the $n = 2$ state of hydrogen atom is : ............ $eV$