Which of the following best explains why different substances have different chemical properties?

• A. Because they have different types and arrangements of atoms in their molecules.
• B. Because all substances are made of the same atoms but in different physical states.
• C. Because chemical properties are determined only by temperature and pressure.
• D. Because substances with the same molecular formula always have identical chemical properties.

Answer: (A)

Verified step by step guidance

1. Understand that chemical properties of substances depend on the nature of their molecules, which are made up of atoms bonded together in specific ways.
2. Recognize that different substances have different types of atoms (elements) and different arrangements (structures) of these atoms within their molecules.
3. Recall that the arrangement and types of atoms affect how molecules interact with other substances, influencing properties like reactivity, acidity, and bonding behavior.
4. Note that physical states (solid, liquid, gas) and external conditions like temperature and pressure can affect physical properties but do not solely determine chemical properties.
5. Conclude that the best explanation for different chemical properties is the variation in types and arrangements of atoms in molecules, rather than just physical state or external conditions.