In the atomic weight determination, Dalton suggested the formula of water as HO and the composition of water as hydrogen = 12% and oxygen = 87.5%, by weight. What should be the atomic weight of oxygen on H-scale, on the basis of this information?

Options

A. 16
B. 8
C. 14
D. 7

Explanation

To determine the atomic weight of oxygen on the hydrogen scale based on Dalton's suggested formula for water (HO) and the given weight percentages of hydrogen and oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Composition**:
- According to the problem, the composition of water is given as:
- Hydrogen = 12%
- Oxygen = 87.5%
- The formula suggested is HO, which implies that for every 1 part of hydrogen, there is 1 part of oxygen by weight.

2. **Setting Up the Equation**:
- Let the atomic weight of hydrogen be represented as 1 (H = 1).
- Let the atomic weight of oxygen be represented as \( x \).
- The total mass of the compound (water) can be expressed as:
\[ \text{Mass of water} = \text{Mass of hydrogen} + \text{Mass of oxygen} = 1 + x \]

3. **Using the Percentage of Oxygen**:
- The percentage of oxygen in the compound can be expressed as:
\[ \text{Percentage of oxygen} = \left( \frac{\text{Mass of oxygen}}{\text{Mass of compound}} \right) \times 100 \]
- Substituting the known values:
\[ 87.5 = \left( \frac{x}{1 + x} \right) \times 100 \]

4. **Solving the Equation**:
- Rearranging the equation gives:
\[ 87.5(1 + x) = 100x \]
- Expanding this:
\[ 87.5 + 87.5x = 100x \]
- Rearranging terms:
\[ 87.5 = 100x - 87.5x \]
\[ 87.5 = 12.5x \]
- Solving for \( x \):
\[ x = \frac{87.5}{12.5} = 7 \]

5. **Conclusion**:
- The atomic weight of oxygen on the hydrogen scale is 7.

### Final Answer:
The atomic weight of oxygen on the hydrogen scale is **7**.

---