"Consider an electron confined in an infinite box of size $d = 0.9$ nm.
Find the momentum of the electron for the stationary levels with $n = 4$ and $n = 9$.
If the electron jumps down from level 5 to the ground state level, what would be the wavelength of the emitted photon?
What are the coordinates of points of highest probability density of electron being there and how many such points are there?
Consider that the box extends from $x = 0$ nm to $x = 0.9$ nm."