Which of the following compounds do not conform to the law of multiple proportion?

Options

A. NaCl and `BaCl_(2)`
B. CaO and `Na_(2)O`
C. `H_(3) PO_(4)` and `Ca_(3) (PO_(4))`
D. All of these

Explanation

To determine which of the given compounds do not conform to the law of multiple proportions, we first need to understand what the law states. The law of multiple proportions states that when two elements combine to form more than one compound, the different masses of one element that combine with a fixed mass of the other element can be expressed as a ratio of small whole numbers.

Let's analyze the compounds provided:

1. **NaCl (Sodium Chloride)** and **BaCl2 (Barium Chloride)**:
- These compounds contain different elements (Sodium and Barium) combined with Chlorine. Since they are not combinations of the same two elements, they do not conform to the law of multiple proportions.

2. **CaO (Calcium Oxide)** and **Na2O (Sodium Oxide)**:
- Again, these compounds consist of different elements (Calcium and Sodium) combined with Oxygen. Thus, they also do not conform to the law of multiple proportions.

3. **H3PO4 (Phosphoric Acid)** and **Ca3(PO4)2 (Calcium Phosphate)**:
- In this case, both compounds contain the phosphate ion (PO4), but they differ in the other elements (Hydrogen in H3PO4 and Calcium in Ca3(PO4)2). Since they involve different elements, they do not conform to the law of multiple proportions.

4. **Conclusion**: Since all the pairs of compounds analyzed involve different elements, none of them conform to the law of multiple proportions.

Thus, the answer to the question is that **all of these compounds do not conform to the law of multiple proportions**.

**Final Answer**: All of these.