Selma hypothesizes that the mass of a sample of water will not change if it is frozen. She conducts an experiment to test her hypothesis. Her experimental steps are as follows:

1. Fill a beaker with 500 mL of water.
2.
3. Place the beaker in the freezer.
4. After the water freezes, place the beaker on the balance and measure its mass.

Which of the following steps is missing from Selma's experiment?

Question

Selma hypothesizes that the mass of a sample of water will not change if it is frozen. She conducts an experiment to test her hypothesis. Her experimental steps are as follows:

1. Fill a beaker with 500 mL of water.
2.                                                 
3. Place the beaker in the freezer.
4. After the water freezes, place the beaker on the balance and     measure its mass.

Which of the following steps is missing from Selma's experiment?

anonymous · Answer

Selma wants to see if the mass changes between the time the water is in its liquid state and the time it's frozen. She wants to know the difference in the masses at both times. In other words, she would have to subtract two values. The fourth step gives her one value.