John Dalton's Atomic Theory laid the conceptual foundation for modern chemistry, yet several of its original postulates have been proven incorrect or incomplete by later discoveries. Which of the foll

Question

John Dalton's Atomic Theory laid the conceptual foundation for modern chemistry, yet several of its original postulates have been proven incorrect or incomplete by later discoveries. Which of the following classical postulates are now considered scientifically inaccurate?

Prashant Kotian · Accepted Answer

Correct answer: A,B. Postulate (A) is inaccurate because the discovery of subatomic particles (protons, neutrons, electrons) and nuclear reactions proved that atoms are internally complex and divisible. Postulate (B) is inaccurate because the discovery of isotopes proved that atoms of the *same* element can have completely different atomic masses (e.g., C-12, C-13, C-14). Postulates (C) and (D) largely hold true for standard chemical combinations and classical stoichiometry (the Law of Definite Proportions and Conservation of Mass).

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