Answer: Physical
Explanation: There are no changes being done to the salt. Think of it this way, if you dissolve the salt in water then boil the water completely, you will have the same salt you started with.
True because energy can change its speed because of temperature and also its direction
Wave speed = (wavelength) x (frequency)
Wavelength = (wave speed) / (frequency)
Wavelength = (9 m/s) / (0.5 Hz)
<em>Wavelength = 18 m</em>