Hydrogen was passed over heated 2 g copper oxide till only copper was left. The mass of copper obtained was 1.6 g. The percentage of oxygen in copper oxide is

Options

A. `80%`
B. `60%`
C. `40%`
D. `20%`

Explanation

To find the percentage of oxygen in copper oxide, we can follow these steps:

### Step 1: Identify the mass of copper oxide and the mass of copper obtained.
- Given:
- Mass of copper oxide = 2 g
- Mass of copper obtained = 1.6 g

### Step 2: Calculate the mass of oxygen in copper oxide.
- The mass of oxygen can be calculated by subtracting the mass of copper obtained from the mass of copper oxide.

\[ \text{Mass of oxygen} = \text{Mass of copper oxide} - \text{Mass of copper} \]

\[ \text{Mass of oxygen} = 2 \, \text{g} - 1.6 \, \text{g} = 0.4 \, \text{g} \]

### Step 3: Calculate the percentage of oxygen in copper oxide.
- The percentage of oxygen in copper oxide can be calculated using the formula:

\[ \text{Percentage of oxygen} = \left( \frac{\text{Mass of oxygen}}{\text{Mass of copper oxide}} \right) \times 100 \]

\[ \text{Percentage of oxygen} = \left( \frac{0.4 \, \text{g}}{2 \, \text{g}} \right) \times 100 \]

\[ \text{Percentage of oxygen} = 0.2 \times 100 = 20\% \]

### Final Answer:
- The percentage of oxygen in copper oxide is **20%**.

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