Which of the following is a reason why Dalton's atomic theory was later found to be incorrect?

• A. Atoms can be created or destroyed in chemical reactions.
• B. All atoms of different elements have the same properties.
• C. Atoms of the same element can have different masses due to isotopes.
• D. Atoms are indivisible and cannot be broken down into smaller particles.

Answer: (C)

Verified step by step guidance

1. Review Dalton's atomic theory and identify its main postulates, such as atoms being indivisible, atoms of the same element being identical, and atoms not being created or destroyed in chemical reactions.
2. Understand that later scientific discoveries showed that atoms are divisible into smaller subatomic particles (protons, neutrons, and electrons), which contradicts the idea that atoms are indivisible.
3. Recognize that isotopes exist, meaning atoms of the same element can have different masses due to varying numbers of neutrons, which contradicts Dalton's claim that all atoms of an element are identical.
4. Note that atoms are neither created nor destroyed in ordinary chemical reactions, which aligns with Dalton's theory, so this point is not a reason for the theory being incorrect.
5. Conclude that the main reason Dalton's atomic theory was found to be incorrect is because atoms of the same element can have different masses due to isotopes, and atoms are divisible into smaller particles.