Which compound has the atom with the highest oxidation number? a. cas b. na3n c. mgso3 d. al(no2)3?

Answer is: c. MgSO₃.
In magnesium sulfite, magnesium has oxidation number +2, sulfur has oxidatidion number +4 and oxygen -2:
+2 + (+4) + 3·(-2) =0.
a) in calcium sulfide, calcium has oxidation number +2 and sulfur -2:
+2 + (-2) = 0.
b) in sodium nitride, sodium has oxidation number +1 and nitrogen -3:
3 · (+1) + (-3) = 0.
d) in aluminium nitrite, aluminium has oxidation number +3, nitrogen +3 and oxygen has -2:
+3 + (+3 + 2 · (-2)) · 3 = 0.

It will fall off and tip over.