How can a periodic table a chemist write the chemical name of a compound from its chemical formula?
a. by determining the number of atoms
b. by identifying the elements
c. by determining the prefixes
d. by determining the subscripts

It's B. by identifying the elements. 

Reasons: 
prefixes are only used for covalent compounds. 

You don't include the number of atoms when you write the chemical name of a compound. 

Subscripts are basically numbers that tell how many atoms of each element is in a compound. It does not identify the name of an element. 

Bis the answerhope it !

They are all solids.