Find the ratio of energies of photons produced due to transition of an election of hydrogen atom from its(i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first permitted level.

Consider the following radioactive decay process:

${}_{84}{}^{218}A\stackrel{\alpha }{⟶}{A}_1\stackrel{{\beta }^{-}}{⟶}{A}_2\stackrel{\gamma }{⟶}{A}_3\stackrel{\alpha }{⟶}{A}_4\stackrel{{\beta }^{+}}{⟶}{A}_5\stackrel{\gamma }{⟶}{A}_6$

The mass number and the atomic number of ${\mathrm{A}}_6$ are given by:

The energy released per fission of nucleus of ${}^{240}\mathrm{X}$ is $200 \mathrm{MeV}$. The energy released if all the atoms in $120 \mathrm{g}$ of pure ${}^{240}\mathrm{X}$ undergo fission is _____$\times {10}^{25} \mathrm{MeV}$.  

(Given $N_A=6\times {10}^{23}$)   

The wavelength of the radiation emitted is ${\lambda }_0$ when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be $\frac{20}{x}{\lambda }_0$. The value of $x$ is________.

The energy levels of an atom is shown is figure.

Which one of these transitions will result in the emission of a photon of wavelength $124.1 \mathrm{nm}$?

Given ($h = 6.62 \times {10}^{–34} \mathrm{J} \mathrm{s}$)