In an experiment, 1.50 g of pure copper(II) oxide was reduced to pure metal by heating with pure carbon. In another experiment, 1.15 g of pure copper was treated with nitric acid and the product formed was heated strongly till no further change was observed. The mass of copper(II) oxide so formed was found to be 1.40 g. The mass of pure metal formed in the first experiment and the law followed are respectively

Options

A. 1.15 g and law of conservation of mass
B. 1.50 g and law of constant proportions
C. 1.23 g and law of constant proportions
D. 2.47 g and law of multiple proportions.

Explanation

To solve the problem, we need to analyze the two experiments described and apply the relevant chemical principles.

### Step-by-Step Solution:

1. **Understanding the First Experiment**:
- In the first experiment, 1.50 g of copper(II) oxide (CuO) is reduced to pure copper (Cu) by heating it with carbon (C).
- The reaction can be represented as:
\[ \text{CuO} + \text{C} \rightarrow \text{Cu} + \text{CO} \]
- Here, we need to determine the mass of pure copper formed from 1.50 g of CuO.

2. **Calculating Molar Masses**:
- Molar mass of CuO = Molar mass of Cu + Molar mass of O
- Molar mass of Cu = 63.55 g/mol
- Molar mass of O = 16.00 g/mol
- Therefore, molar mass of CuO = 63.55 + 16.00 = 79.55 g/mol.

3. **Finding Moles of CuO**:
- Calculate the moles of CuO in 1.50 g:
\[ \text{Moles of CuO} = \frac{\text{mass}}{\text{molar mass}} = \frac{1.50 \, \text{g}}{79.55 \, \text{g/mol}} \approx 0.0188 \, \text{mol} \]

4. **Using Stoichiometry**:
- From the balanced equation, 1 mole of CuO produces 1 mole of Cu.
- Therefore, moles of Cu produced = moles of CuO = 0.0188 mol.

5. **Calculating Mass of Copper Produced**:
- Now, calculate the mass of copper produced:
\[ \text{Mass of Cu} = \text{moles} \times \text{molar mass of Cu} = 0.0188 \, \text{mol} \times 63.55 \, \text{g/mol} \approx 1.19 \, \text{g} \]

6. **Understanding the Second Experiment**:
- In the second experiment, 1.15 g of pure copper is treated with nitric acid, producing copper(II) oxide (CuO).
- The mass of CuO formed is given as 1.40 g.

7. **Identifying the Law Followed**:
- The law followed in these experiments is the **Law of Conservation of Mass**, which states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

### Final Answer:
- The mass of pure metal formed in the first experiment is approximately **1.19 g**.
- The law followed is the **Law of Conservation of Mass**.