Arock weighing 15.0g is placed in a cylinder displacing the volume from 25.0 to 36.2 what is the density of the rock in g/cm3

Density  =mass/volume
The    volume  of  the  rock  is=  volume   of raised  after  rock   was  put  in  the  cylinder which  is  calculated  by  finding  the  difference  in  volumes
  
That  is  36.2 -25=11.2mls
 convert  ml  to  CM^3

     1ml=1cm^3  what  about  11.2ml=11.2cm^3
Density  is  therefore= 15g/11.2  cm^3= 1.34  g/cm^3 

30litre of li2o is 1.0002mole approximately 1 mole