Answer
(a) 3500 nm
(b) $5.30\times10^{14}\,Hz$
Work Step by Step
(a) $c=\nu\lambda$ where $c$ is the speed of light, $\nu$ is the frequency and $\lambda$ is the wavelength.
$\implies\lambda=\frac{c}{\nu}=\frac{3.00\times10^{8}\,m/s}{8.6\times10^{13}\,s^{-1}}=3.5\times10^{-6}\,m=3500\,nm$
(b) $\lambda=566\,nm=566\times10^{-9}\,m$
$\nu=\frac{c}{\lambda}=\frac{3.00\times10^{8}\,m/s}{566\times10^{-9}\,m}=5.30\times10^{14}\,s^{-1}$
$=5.30\times10^{14}\,Hz$
