Recall Dalton's Atomic Theory

The main postulates of Dalton's atomic theory are:

• Matter is made up of tiny, indivisible particles called atoms.
• Atoms of the same element are identical in mass and properties.
• Atoms of different elements differ in mass and properties.
• Compounds are formed when atoms of different elements combine in simple whole-number ratios.
• Chemical reactions involve rearrangement of atoms.

Check each option

A: Compounds are formed when atoms of different elements combine in any ratio.

• Dalton said compounds form in fixed simple whole-number ratios, not in any ratio.
• So this statement is incorrect.

B: Matter consists of indivisible atoms.

• This is one of Dalton's original postulates.
• So this statement is correct within Dalton's theory.

C: chemical reactions involve reorganization of atoms

• Dalton proposed that atoms are neither created nor destroyed in chemical reactions; they are merely rearranged.
• So this statement is correct.

D: All the atoms of a given element have identical properties including identical mass.

• This is also a postulate of Dalton's theory.
• Though modern science shows isotopes exist, the question asks about Dalton's theory.
• So this statement is correct in the context of Dalton's theory.

Conclusion

The incorrect statement is: $\boxed{\text{A}}$

Comparison with stored correct answer

• Derived answer: $\text{A}$
• Stored correct answer: $\text{A}$
• They match.