A compound possesses 8% sulphur by mass. The least molecular mass is

Options

A. `200`
B. `400`
C. `155`
D. `355`

Explanation

To find the least molecular mass of a compound that contains 8% sulfur by mass, we can follow these steps:

### Step 1: Understand the percentage composition
The problem states that the compound has 8% sulfur by mass. This means that in 100 grams of the compound, there are 8 grams of sulfur.

### Step 2: Calculate the mass of sulfur in the compound
From the percentage given:
- Mass of sulfur in 100 g of compound = 8 g

### Step 3: Use the atomic mass of sulfur
The atomic mass of sulfur (S) is approximately 32 g/mol. This means that 1 mole of sulfur weighs 32 grams.

### Step 4: Set up the relationship
We want to find the least molecular mass (M) of the compound. If 8 grams of sulfur corresponds to a certain molecular mass M, we can set up the equation based on the percentage:
\[ \frac{\text{mass of sulfur}}{\text{molecular mass}} = \frac{8}{100} \]
This can be rearranged to find M:
\[ M = \frac{\text{mass of sulfur} \times 100}{\text{percentage of sulfur}} = \frac{32 \times 100}{8} \]

### Step 5: Calculate the molecular mass
Now, substituting the values:
\[ M = \frac{32 \times 100}{8} = \frac{3200}{8} = 400 \text{ g/mol} \]

### Conclusion
The least molecular mass of the compound is 400 g/mol.

### Final Answer
The least molecular mass is **400 g/mol**.

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