D. all of the above, although I do find it hard to believe something like flour would have a melting point, I looked up my answer to double check.
an element whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.
Answer:
Formula of magnesium oxide is MgO and formula of strontium oxide is SrO
Explanation:
Ca, Mg and Sr are same group bivalent metals.
Oxygen is a bivalent element
In general, formula of a compound made of a cation
and an anion
is
for 
When x = y, formula of the compound becomes MA
As both these metals and oxygen are bivalent therefore formula of magnesium oxide is MgO and formula of strontium oxide is SrO.