Final answer:
The chemical formula c) NaCl represents an ionic compound, which is formed by the transfer of electrons between a metal (sodium) and a nonmetal (chlorine) to create oppositely charged ions that attract each other.
Step-by-step explanation:
The chemical formula that shows an ionic compound is c) NaCl. Ionic compounds are formed when metals transfer electrons to nonmetals, creating charged ions that attract each other due to opposite charges.
Sodium (Na) is a metal that loses one electron to form a positively charged sodium ion (Na+), while chlorine (Cl) is a non-metal that gains one electron to form a negatively charged chloride ion (Cl-), resulting in the ionic compound sodium chloride (NaCl).
In contrast, H2O (water) and CH4 (methane) are covalent compounds because they involve nonmetals sharing electrons. CO2 (carbon dioxide) is also a covalent compound.