How to tell if molecule is optically active or racemate?

If it contains chiral carbons then it’s optically active and if it has a chiral centre then it will exist in two forms R and S, and will form a racemic mixture

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)

Yes i think so not 100 percent sure though