Amongst the following which is not a postulate of Dalton's atomic theory

Options

A. Matter is formed of indivisible atoms
B. Under identical conditions of pressure and temperature gases combines and give gaseous products in simple volume ratio
C. During chemical reactions atoms remains conserved and only pass through rearrangement
D. Same atoms have same properties including atomic mass

Answer

To solve the question "Amongst the following which is not a postulate of Dalton's atomic theory," we need to analyze the options given and compare them with the established postulates of Dalton's atomic theory. Here’s a step-by-step breakdown of the solution:

### Step 1: Recall Dalton's Atomic Theory
Dalton's atomic theory consists of several key postulates:
1. All matter is made up of indivisible particles called atoms.
2. Atoms of the same element are identical in mass and properties, while atoms of different elements differ in mass and properties.
3. Atoms cannot be created or destroyed in a chemical reaction.
4. Atoms of different elements combine in simple whole-number ratios to form compounds.
5. Atoms of the same element can combine in different ratios to form different compounds.
6. An atom is the smallest unit of matter that can participate in a chemical reaction.

### Step 2: Analyze Each Option
Now, we will analyze each option provided in the question to determine which one does not align with Dalton's postulates.

1. **Indivisible particles called atoms**: This aligns with the first postulate.
2. **Under identical conditions of pressure and temperature, gases combine and give gaseous products in simple volume ratios**: This statement refers to gas laws (specifically Avogadro's law) and is not a postulate of Dalton's atomic theory.
3. **During chemical reactions, atoms remain conserved and only pass through rearrangement**: This aligns with the third postulate.
4. **Atoms of the same element have the same properties including atomic mass**: This aligns with the second postulate.

### Step 3: Identify the Non-Postulate
From the analysis, the only statement that does not belong to Dalton's atomic theory is the second option regarding gases combining under identical conditions. Therefore, this is the correct answer.

### Final Answer
The option that is not a postulate of Dalton's atomic theory is **Option 2**: "Under identical conditions of pressure and temperature, gases combine and give gaseous products in simple volume ratios."

---