A 51.0 mL
aliquot of a 1.60 M
solution is diluted to a total volume of 258 mL.
A 129 mL
portion of that solution is diluted by adding 143 mL
of water. What is the final concentration? Assume the volumes are additive.

the answer is the

it means there are 3 atoms of oxygen

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.

the answer is option a.