In basic chemistry, a change in which one or more new substances with different properties are formed is called what type of change?

Introduction / Context:
In elementary chemistry, changes in matter are broadly classified into physical changes and chemical changes. This distinction helps students understand whether the identity of a substance has altered or whether only its form has changed. Physical changes typically involve changes in state, shape, or appearance without forming new substances, while chemical changes result in the formation of entirely new substances with different properties. This question asks you to recall the term used when one or more new substances are produced during a change.

Given Data / Assumptions:

• The question describes a change where one or more new substances are formed.
• Options include physical change, chemical change, rusting, and galvanisation.
• Rusting and galvanisation are specific processes related to metals and corrosion.
• We assume standard school level definitions of physical and chemical changes.

Concept / Approach:
A chemical change, also called a chemical reaction, is defined as a process in which one or more substances are transformed into new substances with different compositions and properties. Signs of chemical change may include colour change, gas evolution, formation of a precipitate, or energy change. Physical changes, such as melting ice or breaking a glass, do not produce new substances; they simply alter the physical form or state. Rusting is a specific chemical change involving iron and oxygen, and galvanisation is a protective process to prevent rusting. The general definition in the question clearly matches a chemical change.

Step-by-Step Solution:
Step 1: Read the description in the question: one or more new substances are formed, and properties change. Step 2: Recall that physical changes do not create new substances; they only change the physical state or appearance. Step 3: Remember that the formation of new substances with new properties is the hallmark of a chemical change. Step 4: Recognise that rusting is one specific example of a chemical change but does not name the general category. Step 5: Note that galvanisation is a process of coating a metal with zinc to prevent corrosion, not a general term for a type of change. Step 6: Conclude that the correct general term for such a change is chemical change and select that option.

Verification / Alternative check:
Textbooks introduce chemical change with examples such as burning of paper, digestion of food, rusting of iron, and souring of milk. In each case, new substances are formed that cannot easily be converted back to the original by simple physical means. These examples are contrasted with physical changes like freezing water or dissolving sugar, where no new substance is formed and the process may be reversible. The definition in these sources mirrors the wording in the question and labels such transformations as chemical changes. This confirms that chemical change is the correct answer.

Why Other Options Are Wrong:
A physical change does not involve the formation of new substances; the material retains its original chemical identity even if its form or state changes. Rusting is a specific chemical process affecting iron and does not name the general type of change described. Galvanisation is a protective surface treatment applied to metals and is not itself a classification of change based on whether new substances form. Therefore, none of these options matches the general definition in the question except chemical change.

Common Pitfalls:
Students sometimes confuse specific examples with broader categories, for instance thinking that rusting is the name of the category rather than one example of a chemical change. Another pitfall is misclassifying reversible processes like dissolving or melting as chemical changes even though no new substances are formed. To avoid such errors, focus on whether the chemical composition of the substance changes and whether new substances with different properties are produced. If so, it is a chemical change; if only the physical form changes, it is a physical change.

Final Answer:
A change in which one or more new substances are formed is called a chemical change that produces one or more new substances.