density= mass/volume
we need the volume of the metal to find the density, in which case the answer would be 64.2/volume=density
5- sr +2 O -2. SrO
6- Mg +2 F-1 MgF2
7- B+3 P-3 BP
8- Li +1 N-3 Li3N
9- Ba +2 Br -1 BaBr2
10- Al +3 P -3 AlP
Molar mass MgCO3 => 84.31 g/mol
1 mole MgCO3 ----------- 84.31 g
1.5 moles MgCO3-------- ??
1.5 x 84.31 / 1 => 126.465 g
Because M = mol/L or mL. 15.0 x 0.350/42.0 = M