Bending an iron nail is what type of change?

Correct answer: Physical change

Direct answer: A, physical change. A physical change alters a substance’s shape, size, state, or appearance without producing a new substance. When an iron nail is bent, the iron remains iron; only its shape changes. The change may not be easily reversible if the nail is permanently bent, but reversibility is not the only test. The key test is whether a new chemical substance has formed. Option A is correct. Option B, chemical change, is wrong because bending alone does not create a new substance or change iron into another material. Option C, fermentation, is a biological or chemical process in which microorganisms convert substances such as sugars; it has no connection with merely bending iron. Option D, combustion, requires burning and reaction with oxygen, whereas no burning occurs here. Memory cue: changed form but same material means physical change; rusting would be chemical, but bending is not rusting.