Sodium has an atomic number of 11 and has a net charge of 0. when sodium combines with chlorine, it has a net charge of +1. why?

Sodium has an atomic number 11, it means there are 11 electrons in sodium atom and has a net charge zero what when it combines with chlorine it loses one electron and get charge of +1. when and atom loses an electron it gets positive charge and when atom gains electron it gets negative charge. chlorine makes an anion and sodium makes cation and they are oppositely charged so they react with each other.

1. and 2. question: in which equation? or i don't understand you, 3. a), 4. c), 5. c), 6. b), 7. d), 8. d) if small number is underlined(behind symbol) , b) if big number is underlined(in front of symbol)9. what is underlined there? 10. c)