1.) NaCl(s) 2.) NaCl(aq) 3.) H2O(s) 4.) H20(g) I honestly don't understand this question. Conductor of what?
Which substance is the best conductor?
NaCl(s) is table salt in solid form.
NaCl(aq) is table salt in aqueous solution (salt water for example)
H2O(s) is solid water, otherwise known as ice
H20(g) is gaseous water, otherwise known as water vapor
H2O has no free electrons and in pure form does not conduct electricity in solid or gaseous state.
In solid state, the NaCl molecules are tightly interconnected in a crystalline structure with no free electrons. Solid table salt also doesn't conduct electricity.
However, table salt can dissolve in water (or in some other aqueous solution) to form Na+ and CL- ions and form a great electrical conductor.
In Chemistry, a compound can be considered a conductor of electricity if charged particles are formed (usually in an aq. solution).
Since there is only one aqueous choice amongst the answers provided, the NaCl will ionize in solution into Na+ & Cl- ions, allowing it to freely conduct electricity. When a compound ionizes in water it is considered an electrolyte and is able to conduct electricity.