When MGCl2(magnesium chloride)is dissolved in water how many particles are in solution?

Which statement is true about ionic compounds?

Ahypothrticalax type of ceramic material is known to have a density of 2.10 g/cm3 and a unit cell of cubic symmetry with a cell edge length of 0.57 nm. the atomic weights of the a and x elements are 28.5and 30.0 g/mol, respectively. on the basis of this information, which of the following crystal structures is (are) possible for this material: sodium chloride, cesium chloride, or zinc blende

If a polyatomic ionic compound has gained two hydrogen ions, then how does its name begin?