Issued as a cumulative or non-cumulative L/C, the former allows for unused credit amounts to rollover into subsequent periods while the latter maintains a fixed amount of credit available each period.
average atomic mass of magnesium is 24.3 g/mole so 24.3 X 1.56 X1021 / 6.02 X1023 = .063 grams.
Magnesium Chloride is an inorganic salt, which has the chemical formula of MgCl2 and molecular weight 95.210 g/mol. Predominantly magnesium chloride exists as various hydrates, particularly hexahydrate MgCl2 *6H2O having the molecular weight of 203.301 g/mol.