ok so 8. is 15 because of sig figs in expression
9. 25nm = 25*10^-9m or 2.5*10^-8m
10. density=mass/volume so volume=mass/density = 3.85*10^7
11. 0.65g/cm^3
12. 245mL
13.7.13g/cm^3
14.1mL
Hope this helps!!! And great job!!! Keep up the hard work!!
Thank you!