Which of the following chemical reactions is reversible? A. The neutralization of an acid.
B. The burning of wood.
C. The freezing of water into ice
D. The dehydration of copper sulfate (CuSO4).

the freezing of water into ice is reversible because you can still melt that I e and reverse it back into it's liquid form.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.