According to Dalton's atomic theory, which statement is true about atoms of the same element?

• A. Atoms can be divided in chemical reactions
• B. Atoms of the same element are identical
• C. Atoms of the same element have different masses
• D. Atoms are not used in chemical reactions

Answer: (B)

This question tests whether Dalton's view that atoms of the same element are identical holds true. In Dalton’s model, matter is made of atoms, and all atoms of a given element have the same mass and properties, so they behave the same chemically. This sameness is what allows atoms to combine in fixed ratios to form compounds, and it’s why atoms of the same element are considered identical. The other ideas don’t fit Dalton’s model: chemical reactions involve rearranging whole atoms rather than splitting them; atoms of the same element having different masses would go against the notion of identical atoms; and saying atoms aren’t used in chemical reactions contradicts the idea that reactions are about atoms forming and breaking bonds.