Answer
See the answer below.
Work Step by Step
a) The 253.62 nm is the most energetic because it has a lower wavelength (higher frequency).
b)
$c=\lambda\times\nu$
$\nu=2.998\times10^8\ m/s\div 253.652\ times10^{-9}\ m=11.82\times10^{14}\ 1/s$
$E=h\times\nu$
$E=6.626\times10^{-34}\ J.s\times 11.82\times10^{14}\ 1/s=7.83\times10^{-19}\ J$
c) 404.656 and 435.833 nm are present, both with a blue color.
