Answer is: CaCl₂(s), calcium chloride.
Calcium cations and chlorine anions have a crystal structure in this solid inorganic salt. Ions have the ordered arrangement.
Ethane (C₂H₆) is gas, g is chemistry abbreviations or physical state symbol for gas, gases do not have a crystal structure.
Methanol (CH₃OH) is liquid, l is chemistry abbreviations or physical state symbol for liquids, it do not have a crystal structure.
Calcium iodide is dissolved in water, aqueous solution (aq) do not have a crystal structure.