Based on the characteristics of the unknown compound—very strong bonds, ions that dissociate in water, high melting and boiling points, and high conductivity in aqueous solutions—the compounds that share similar characteristics are:
B. KCl (potassium chloride)
D. NaCl (sodium chloride)
F. MgSO4 (magnesium sulfate)
These compounds are ionic solids that dissociate into ions when dissolved in water, resulting in high conductivity and high melting and boiling points.