What minerals that are heavy, durable, and chemically resistant are likely to be found in what kind of deposites?

Minerals that are heavy, durable, and chemically resistant are likely to be found in placer deposits. A placer deposit is an accumulation of valuable minerals formed by gravity separation during sedimentary processes.

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)