In order to retrieve the soluble salt from the solution, crystallization must be carried out.<span />
I attached the working and the answer to both questions below.
Please note that C = speed of light, ν = frequency, λ= wavelength
<span>The wavelength of a 2.28 x 10</span>¹⁷<span> Hz wave is
1.31 </span>
×<span>
10</span>
⁷ cm<span>
The frequency of a 7.30 x 10</span>⁻⁵<span> m wave
4.11 </span>
×<span>
10</span>
¹² s⁻¹
D. Sonic booms. Hope this helps