Question

1. which statement best describes what happens when a nail rusts? it shrinks in size without any change in its composition. it is dissolved completely by water. it undergoes a chemical change where a new substance is formed. it undergoes a physical change where its appearance changes but the substance stays the same.

Explanation:

Rusting of a nail is a chemical reaction where iron in the nail reacts with oxygen and water to form iron - oxide (rust), a new substance. A physical change only affects the appearance without changing the chemical composition. Dissolving in water is a different type of physical - chemical process not related to rusting. Since rusting results in the formation of a new substance, it is a chemical change.

Answer:

It undergoes a chemical change where a new substance is formed.