Rewrite 5 to have 3 sig figs

Not sure which one you wanted, so here a few different ones:

Decimal notation: 5.00  

Scientific notation: 5.00 ×

E notation: 5.00e+0

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.