Answer:
The densest materials are rock and bottle of soda.
Step-by-step explanation:
The density of material is given by,
Density =

Case 1: Rock
Density =

Density = 2000

Case 2: Pillow
Density =

Density = 20

Case 3: Bottle of soda
Density =

Density = 1000

Case 4: Load of bread
Density =

Density = 100

The densest materials are rock and bottle of soda.