40 ! solve question on page 2 & 4.

(1)

Variables:

Test Variable:

The test variable is temperature/ heat.

Outcome variable:

The response/outcome variable is mass.

Controls:

Negative Control:

A solid stick of butter at room temperature.

Positive Control:

A stick of butter whose mass before and after heating is known.

(2)

Upon measurement, the mass of the butter was not found to be changing drastically. Butter does not lose or gain mass when heated to meting stage. A negligible decrease in mass take place when the moisture in the solid butter evaporates. Other than that, both solid and molten butter have similar masses.

The hypothesis,"If butter is heated, there was no mass created when it melted" was proven to be correct.

Explanation:

In an experiment, variables are quantities whose cause-effect relationships require study. Variables do not have a fixed value. In experimental design, there are two kinds of variables:Independent variable or test variableDependent variable or response variable

Independent Variable:

Independent or test variable is the variable that changes during the experiment and the effect of which is determined. For example, in the current experiment, we are investigating the effect of heat or state change on the mass of butter. Therefore, heat.state change will be the test variable.

Dependent/ Response Variable:

This is the variable that changes in response to changes in the independent variable. In the current experiment, mass is the response variable because it is being affected by heating.

Controls:

In an experimental design, controls determine the reliability and fidelity of an experiment. These are samples/individuals that are either not subjected to the independent variable or have previously been tested to give positive results. Basically, the controls are standards to which data can be compared.

Positive Control:

A positive control is a sample that has been tested to give positive results for the particular experiment in response to the independent variable. For example, in this experiment, the known masses (before and after melting) are positive controls. They are known values to which we can compare our results.

Negative Control:

A negative control is a group of samples that does not receive the treatment. Negative controls provide confirmation that the change in the response variable is only due to the test variable, not because of other factors.

Is there any pictures in the question? i can’t answer the question without seeing the model.