Question

which best describes the purpose of a controlled experiment?
to make sure the results of the experiment support the hypothesis
to prevent a dangerous condition resulting from a reaction
to examine whether one variable causes a change in another
to prevent an undesired change in a variable

Explanation:

• Option 1: A controlled experiment doesn't aim to ensure results support the hypothesis (results can refute it too).
• Option 2: Safety measures (like preventing dangerous reactions) are not the main purpose of a controlled experiment.
• Option 3: In a controlled experiment, we manipulate one variable (independent) and observe its effect on another (dependent), while controlling other variables. This is to test if one variable causes a change in another.
• Option 4: Preventing undesired change in a variable is part of controlling variables, but not the main purpose of the experiment. The main purpose is to test causal relationships between variables.

Answer:

C. to examine whether one variable causes a change in another