1. Bread and apple as the 2 food. They both have different densities. Apple should have a higher density, unlike bread, it does not have a lot of carbon dioxide spaces in between.

2. The volume of liquid is measured by using a measuring cylinder. It is commonly found in any labs. The volume of a solid is measured depending on its shape. We can either use formulas, like calculating volume of cubes or spheres, or putting the solid into a specific volume of water and find the rise of water level after putting the object in. That rise of water is the volume of object.

3. We can determine the density of the object by dividing its mass by its volume.

4. As said before, we can use a measuring cylinder. But if the object is too big, we can also use an overflow vessel.

5. A cylinder is the shape of the long circular tube like structure. Example of an cylindrical object includes a water bottle.

6. Radius is the the length of a circle from its center to its perimeter edge. We might need to measure an objects radius in order to calculate its area or volume or arc length etc.

7. There should be 2 types of water displacement described. One is the one I just mentioned above, by putting an object in a cylinder with water and measure the water level rise to determine its volume. The other type of water displacement is a method to collect gas by putting an inverted beaker into a tank of water and connecting a tube to it, while releasing gas to the tube. The gas will displace the water and you'll get a beaker of gas.

8. Density x volume is the mass, mass / volume is the density, and mass / density is the volume.

9. Again, density = mass/volume. Just measuring the mass and the volume of the object by using the methods above, and using a balance for the mass, then complete the formula to find the density.