The formula for density is p=m/V
p is density
m is mass
V is volume ( *this has to be capital to mean the same*)
We know the mass m is 2g
and the Volume V is 6 mL
So divided 2/6
p= 0.33333 g/mL
your density is 0.333333g/mL
Make sure to check your significant figures if that applies. It is 1/3 or 0.3 repeating for eternity. Also make sure to put g/mL as a classification.