Frequency of a light wave (υ) = $\frac{1}{\text{Time period}}$ = $\frac{1}{2.0 \times 10^{-10}}$ = 5 × $10^9\,\mathrm{s}^{-1}$ Wavelength of light wave (λ) = $\frac{c}{\upsilon}$ = $\frac{3 \times 10^8}{5 \times 10^9}$ = 6.0 × $10^{-2}\,\mathrm{m}$ Wavenumber of light wave $\left(\overset{-}{v}\right)$ = $\frac{1}{\lambda}$ = $\frac{1}{6.0 \times 10^{-2}}$ = 16.6 $\mathrm{m}^{-1}$ Therefore, wavelength, frequency and wavenumber of the light wave are 6.0 × $10^{-2}$ m, 5 × $10^9\,\mathrm{s}^{-1}$ and 16.6 $\mathrm{m}^{-1}$ respectively.