Find the number of compounds from the following in which the element in the anionic part is in the minimum oxidation state of it :

$\mathrm{LiH}$, ${\mathrm{Mg}}_3{\mathrm{Bi}}_2$, ${\mathrm{Al}}_4{\mathrm{C}}_3$, ${\mathrm{Ca}}_3{\mathrm{P}}_2$, ${\mathrm{BaO}}_2$

Compound           Minimum oxidation state of anion

$\mathrm{LiH}$                             -1

${\mathrm{Mg}}_3{\mathrm{Bi}}_2$                     -3

${\mathrm{Al}}_4{\mathrm{C}}_3$                        -4

${\mathrm{Ca}}_3{\mathrm{P}}_2$                       -3

Hence, the number of compounds from the following in which the element in the anionic part is in the minimum oxidation state is 4.