In stars, helium can sometimes be fused into carbon and heavier elements (in their final stages of life). why didn't the same fusion processes produce carbon and heavier elements in the early universe?

Because the early universe was so hot that even tough the conditions to create heavy elements were there, they will break apart immediately after their formation because it was too hot for the heavy elements to remain stable. It was only later after the universe cold down that elements weren’t break apart and the process of forming heavy elements could begin.

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.

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.