<span>The formula in terms of the oxidation numbers for the elements. The sum of the oxidation numbers for a compound must be zero.
Ca3N2
KBr
Cs2S
CsF</span>
2) Solubility is how much solvent will dissolve in solute.
I think by writing electronic configuration.
That’s a hard one, but honestly i would go with a.
... indicates that it also has a high concentration of Hydroxide (OH) and that it is more basic.