<span>3. MgCl2
For each salt, determine what acid and base were used to create it by separating the salt into it's cation and anion. From there, determine the acid and base used to create the salt by adding the appropriate number of hydroxyl group(s) to the cation and hydrogen to the anion. So:
LiClO4 -> Li, ClO4 -> LiOH + HClO4.
LiOH is a strong base, and HClO4 is a strong acid.
CsBr2 -> Cs, Br2 -> CsOH + HBr2
CsOH is a strong base, and HBr2 is a strong acid.
MgCl2 -> Mg, Cl2 -> Mg(OH)2 + HCl
Mg(OH)2 is not a strong soluble base
HCl is a strong acid.
Therefore MgCl2 is the correct salt.
Ba(NO3)2 -> Ba, NO3 -> Ba(OH)2 + HNO3
Ba(OH)2 is a strong base, and HNO3 is a strong acid.
NaI -> Na, I -> NaOH + HI
NaOH is a strong base, and HI is a strong acid.</span>
I believe the answer is MgCl, this is because the bases of group one elements (alkali metals) such as sodium, lithium , and cesium, are all strong bases unlike those of group 2 and group 3. The bases of group one elements ( NaOH, LiOH, CsOH) all readily dissolve in water forming strong soluble base. Then between a base of Ba (Ba(OH)2)and that of Mg, (Mg(OH)2), the one for Ba is more stronger because Ba is more reactive than that of Mg because it is not readily dissolve in water ( less soluble in water to give OH- ions)
