Amongst the following statements, that which was not proposed Dalton was :

Options

A. matter consists of indivisible atoms.
B. when gases combine or reproduced in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same T & P.
C. all the atoms of a given element have identical mass. Atoms of different elements differ in mass.
D. Chemical reactions involve recorganization of atoms. These are neither created nor destroyed in a chemical reaction.

Answer

To solve the question regarding which statement was not proposed by Dalton, we will analyze each of the provided statements in the context of Dalton's atomic theory.

### Step-by-Step Solution:

1. **Understanding Dalton's Atomic Theory**:
- Dalton proposed that matter is made up of atoms, which are indivisible particles.
- He stated that all atoms of a given element are identical in mass and properties, while atoms of different elements differ in mass and properties.
- He also proposed that chemical reactions involve the rearrangement of atoms and that atoms are neither created nor destroyed in these reactions.

2. **Analyzing Each Statement**:
- **Statement A**: "The matter consists of individual atoms."
- This aligns with Dalton's theory, which states that matter is composed of atoms. Thus, this statement is proposed by Dalton.

- **Statement B**: "When gases combine or reproduce in a chemical reaction, they do so in a simple ratio by volume provided all gases are at the same temperature and pressure."
- This statement is related to the laws of combining volumes of gases, which was later discussed by Avogadro, not Dalton. Therefore, this statement is **not** proposed by Dalton.

- **Statement C**: "All the atoms of given elements have identical mass. Atoms of different elements differ in mass."
- This is consistent with Dalton's atomic theory, which states that all atoms of a given element are identical in mass and properties. Hence, this statement is proposed by Dalton.

- **Statement D**: "Chemical reactions involve reorganization of atoms and these are neither created nor destroyed in a chemical reaction."
- This is a fundamental postulate of Dalton's atomic theory, confirming that atoms are rearranged in reactions but not created or destroyed. Thus, this statement is proposed by Dalton.

3. **Conclusion**:
- The only statement that was **not** proposed by Dalton is **Statement B**.

### Final Answer:
**Statement B** is the correct answer as it was not proposed by Dalton.

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