You take the mass number and subtract the number of neutrons
Well I believe the claim is if you use all its energy fr a long period of time it does so the claim is if the light is left on the battery runs out and flashlight stops working
velocity of the diver is vertically downwards
given that

time of motion of the diver

so the displacement is given by



so it will be displaced downwards by 12.75 m
The lowest and highest wavelengths of this part of the electromagnetic spectrum are:


The frequency and the wavelenght of an electromagnetic wave are related by

where c is the speed of light and f the frequency. By using this equation, we can find the frequencies that corresponds to the lowest and highest wavelengths of this part of the spectrum:


So, the highest frequency associated with this part of the spectrum is the one corresponding to the lowest wavelength: