Calculate the wavenumber of the photon emitted during transition from the orbit of $n=2$ to $n=1$ in a hydrogen atom. $[R_H = 109677 \ cm^{-1}]$ (in $cm^{-1}$)

$A$ $50 \, W$ 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 $......$.
$[ \text{Given} : h=6.63 \times 10^{-34} \, J \cdot s \text{ and } c=3.0 \times 10^{8} \, m \cdot s^{-1} ]$

The potential energy of an electron in an atom is given by:

If the ratio of the area of two orbits of an $H$ atom is $4 : 1$,then the ratio of the frequency of the $e^-$ in these two orbits is:

Which one of the following is not the characteristic of Planck's quantum theory of radiation?

When an electron jumps from a lower to a higher orbit,its energy