Magnesium is used in lightweight alloys for airplane bodies and other structures. The metal is obtained from seawater in a process that includes precipitation, neutralization, evaporation, and electrolysis. How many kilograms of magnesium can be obtained from 4.18 km^3 of seawater if the initial Mg+2 concentration is 0.20% by mass? (d of seawater= 1.04 g/mL) ___ x 10 ^__ kg Mg steps would be helpful