Which one the following combinations illustrate law of reciprocal proportions ?

Options

A. `N_(2)O_(3), N_(2)O_(4),N_(2)O_(5)`
B. `NaCl,NaBr, NaI`
C. `CS_(2), CO_(2),SO_(2)`
D. `PH_(3),P_(2)O_(3),P_(2)O_(5)`

Answer

To determine which combination illustrates the law of reciprocal proportions, we will analyze the given data regarding the compounds hydrogen peroxide (H2O2) and water (H2O).

### Step-by-Step Solution:

1. **Identify the Compounds and Their Composition**:
- We have two compounds: Hydrogen Peroxide (H2O2) and Water (H2O).
- The percentage composition of hydrogen in H2O2 is given as 5.93%, and in H2O it is 11.2%.

2. **Calculate the Mass of Hydrogen in Each Compound**:
- In H2O2, there are 2 hydrogen atoms. The molar mass of hydrogen is approximately 1 g/mol.
- Therefore, the mass of hydrogen in H2O2 = 2 * 1 g = 2 g.
- In H2O, there is 1 hydrogen atom.
- Therefore, the mass of hydrogen in H2O = 1 * 1 g = 1 g.

3. **Calculate the Mass of Oxygen in Each Compound**:
- In H2O2, there are 2 oxygen atoms. The molar mass of oxygen is approximately 16 g/mol.
- Therefore, the mass of oxygen in H2O2 = 2 * 16 g = 32 g.
- In H2O, there is 1 oxygen atom.
- Therefore, the mass of oxygen in H2O = 1 * 16 g = 16 g.

4. **Establish the Ratios**:
- For H2O2, the ratio of hydrogen to oxygen is:
- Mass of hydrogen : Mass of oxygen = 2 g : 32 g = 1 : 16.
- For H2O, the ratio of hydrogen to oxygen is:
- Mass of hydrogen : Mass of oxygen = 1 g : 16 g = 1 : 16.

5. **Analyze the Ratios**:
- The mass of hydrogen remains constant (1 g in H2O and 2 g in H2O2), while the mass of oxygen varies in simple ratios (16 g in both cases).
- This illustrates the law of reciprocal proportions, which states that when two elements combine with a fixed mass of a third element, the masses of the two elements that combine with the fixed mass are in a simple ratio.

6. **Conclusion**:
- Therefore, the correct option that illustrates the law of reciprocal proportions is **D**.