$A$ bulb emits monochromatic yellow light of the wavelength $0.57 \ \mu m$. If the rate of emission of quanta per second of the bulb is $14.33 \times 10^{19}$, the power of the bulb (in $Watt$) is $.....$

Find the frequency and wavelength of light required for the ionization of the solution. (Ionization energy of the solution $= 8.2 \times 10^{-19} \ J$)

Write down the postulates of Bohr's model for the hydrogen atom.

The energy associated with the electron in the first orbit of a hydrogen atom is $-2.18 \times 10^{-18} \ J$. The frequency of the light required (in $Hz$) to excite the electron to the fifth orbit is $(h = 6.6 \times 10^{-34} \ Js)$

The energy (in $eV$) associated with the electron in the $1^{st}$ orbit of $Li^{2+}$ is

What will be the ratio of the wavelength of the third line of the Balmer series in the $He^{+}$ ion spectrum to the first line of the Balmer series in the $Li^{2+}$ ion spectrum?