Which of the following is an electrolyte?
a. NaCl (s)
d. NaCl (aq)
An electrolyte is a substance that is capable of conducting electricity. To identify an electrolyte when gives formulas we must first make a list.
List of electrolytes: Ionic compounds (aqueous), Metals, Strong Acids and Strong Bases.
Let's now take a look at the answer choices.
NaCl (s) is an ionic compound since it is composed of a metal and a nonmetal. However it is solid and not aqueous. Ionic compounds do not conduct electricity in their solid form,
H2O water is a molecular compound and is therefore not an electrolyte (it can conduct electricity just a little bit on its own).
CCl4 is another molecular compound (all nonmetal atoms) and can not be our answer choice.
NaCl (aq) is an ionic compound that is dissolved in water (hence aq) and is therefore the correct answer choice.