Which one of the following pairs of compound illustrates the law of multiple proportion (A) H2O, Na2O (B) MgO, Na2O (C) Na2O, BaO (D) SnCl2, SnCl4

Options

A. `PH_3, HCl`
B. `PbO, PbO_2`
C. `H_2S, SO_2`
D. `CuCl_2, CuSO_4`

Answer

To solve the question "Which one of the following pairs of compounds illustrates the law of multiple proportions?", we need to understand the law of multiple proportions and analyze the given options.

### Step-by-Step Solution:

1. **Understand the Law of Multiple Proportions**:
The law states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers.

2. **Analyze Each Option**:
- **Option A: H2O and Na2O**
- H2O consists of hydrogen and oxygen, while Na2O consists of sodium and oxygen. Here, we have three different elements (H, O, Na) and not two elements forming multiple compounds. Therefore, this option does not illustrate the law.

- **Option B: MgO and Na2O**
- MgO consists of magnesium and oxygen, while Na2O consists of sodium and oxygen. Again, we have three different elements (Mg, O, Na) and not two elements forming multiple compounds. Thus, this option does not illustrate the law.

- **Option C: Na2O and BaO**
- Na2O consists of sodium and oxygen, while BaO consists of barium and oxygen. Here, we again have three different elements (Na, O, Ba) and not two elements forming multiple compounds. Therefore, this option does not illustrate the law.

- **Option D: SnCl2 and SnCl4**
- SnCl2 and SnCl4 consist of tin (Sn) and chlorine (Cl). Here, we have two elements (Sn and Cl) forming two different compounds. If we fix the mass of Sn, the mass of Cl in SnCl2 and SnCl4 can be expressed in a ratio of small whole numbers (2:4 or 1:2). This option satisfies the law of multiple proportions.

3. **Conclusion**:
- The only option that illustrates the law of multiple proportions is **Option D: SnCl2 and SnCl4**.

### Final Answer:
**Option D: SnCl2 and SnCl4 illustrates the law of multiple proportions.**