What is the name of the tool to the right that was used to measure the volume of the water and the rock?

Graduated Cylinder

Explanation:

Basically a graduated cylinder is used to measure the volume of a liquid with least count of 1 mililiter. While the volume of a liquid is directly measured through a graduated cylinder, the volume of a rock is measured in a bit different way.

For measuring volume of rock, first the reading of water level for beaker with in a graduated cylinder (filled with water but without stone) is taken. Now a rock is placed inside it. Here the level of water increases. This change in water level is noted and converted into volume to find the exact volume of stone.

Thus, a graduated cylinder can be used to measure the he volume of the water and the rock

Graduated cylinder

Explanation:

To derive the volume of an irregular object, you simply place it into a graduated cylinder filled up to a certain level with water. Then, you measure the displacement of the water between the original level and the level that the water is at after you place the object in. This will be in milliliters (mL), and since 1mL is equivalent to 1cm^3m you have your answer when you subtract the two volumes of water.