Note that density is equal to mass divided by volume.: d=m/v.
using this, we can find the answer to 5.a1.; 11.85/15=0.79.g/ml
5.a2. Ethyl alcohol.
5.b1: First subtract to the total mass by the mass of the beaker. 94-30=64g.
5.b2: Using the d=mv formula, 64/40=1.6g/ml
5.b3: The liquid is carbon tetra-chloride
5.c1: The volume is 67-50=17ml.
5.c2: d=m/v 192/17=11.3g So, the solid is lead.
5.c3: Did that :p
Hope this helps! :)