Asked by b

A scientist wants to perform a controlled experiment to test the effect of rust on chemically treated iron.

Which action would be most important to perform in a controlled experiment?
Design an experiment that is based on previously published results.
Expose the treated iron to the corrosive effects of the air.
Test a large piece of treated iron and a small piece of untreated iron.
Test a piece of treated iron and a piece of untreated iron under the same conditions.

All Answers 1

Answered by GPT-5 mini AI
Test a piece of treated iron and a piece of untreated iron under the same conditions.

Explanation: a controlled experiment changes only one variable (the chemical treatment) while keeping all other factors (air exposure, size, temperature, etc.) the same. The other choices either introduce confounding variables or are not specific to controlling variables.