In an experiment, 2.4 g of iron oxide on iron. In another experiment, 2.9 g of iron oxide gave 2.09 g of iron on reduction. Which law is ilustrated from the above data?

Options

A. Law of constant proportions
B. Law of multiple proportions
C. Law of conservation of mass
D. Law of reciprocal proportions

Answer

To determine which law of chemistry is illustrated by the given data, we will analyze the mass of iron oxide and the mass of iron produced in two separate experiments.

### Step-by-Step Solution:

1. **Identify the Data from the Experiments**:
- In the first experiment:
- Mass of iron oxide = 2.4 g
- Mass of iron produced = 1.68 g
- In the second experiment:
- Mass of iron oxide = 2.9 g
- Mass of iron produced = 2.09 g

2. **Calculate the Mass of Oxygen in Each Experiment**:
- For the first experiment:
- Mass of oxygen = Mass of iron oxide - Mass of iron
- Mass of oxygen = 2.4 g - 1.68 g = 0.72 g
- For the second experiment:
- Mass of oxygen = Mass of iron oxide - Mass of iron
- Mass of oxygen = 2.9 g - 2.09 g = 0.81 g

3. **Calculate the Ratio of Masses of Iron to Oxygen**:
- For the first experiment:
- Ratio of iron to oxygen = Mass of iron / Mass of oxygen
- Ratio = 1.68 g / 0.72 g = 2.33 (or simplified to 7:3)
- For the second experiment:
- Ratio of iron to oxygen = Mass of iron / Mass of oxygen
- Ratio = 2.09 g / 0.81 g = 2.58 (or simplified to 7:3)

4. **Compare the Ratios**:
- Both experiments yield the same ratio of iron to oxygen (7:3), indicating that the elements combine in a fixed proportion by mass.

5. **Conclusion**:
- The law illustrated by the data is the **Law of Constant Proportions** (or Law of Definite Proportions), which states that a chemical compound always contains its component elements in fixed ratio by mass, regardless of the source or method of preparation.