How do you know if a equation is balanced or unbalanced

A chemical equation is only balanced once there are equal numbers of all types of element on both sides of the equation

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)

Hi + naoh -> h2o + nal