Answer :
Actual volume=Final Volume-initial volume
[tex]\\ \sf\longmapsto 50ml-30ml=20ml[/tex]
Now
[tex]\\ \sf\longmapsto Density=\dfrac{Mass}{Volume}[/tex]
[tex]\\ \sf\longmapsto Density=\dfrac{10}{20}[/tex]
[tex]\\ \sf\longmapsto Density=2g/ml[/tex]