Answer
The energy of a photon of this wavelength is $6.112\times10^{-19}J$.
Work Step by Step
*Strategy:
The following formula would be used in dealing with this question. $$E=h\times\nu=\frac{h\times c}{\lambda}$$
$E$ : energy of a photon
$h$ : Planck's constant ($h\approx6.626\times10^{-34}J.s$)
$\nu$ : frequency of the UV light
$c$ : speed of light in a vacuum ($c\approx2.998\times10^8m/s$)
$\lambda$ : wavelength of the UV light (here $\lambda=325nm=3.25\times10^{-7}m$)
Therefore, the energy of a photon of this wavelength is:
$E=\frac{h\times c}{\lambda}=\frac{(6.626\times10^{-34})\times(2.998\times10^8)}{3.25\times10^{-7}}\approx6.112\times10^{-19}J$
