The number of moles in 16 g calcium is 0.4. What is the molar mass of Ca atoms?

Options

A. `4 g mol^(-1)`
B. `6.4 g mol^(-1)`
C. `0.04g mol^(-1)`
D. `40 g mol^(-1)`

Answer

To find the molar mass of calcium (Ca) atoms based on the given information, we can use the formula for calculating the number of moles:

### Step-by-Step Solution:

1. **Understand the Formula**: The number of moles (n) is calculated using the formula:
\[ n = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]
Here, we need to find the molar mass of calcium.

2. **Identify Given Values**: From the question, we know:
- Number of moles (n) = 0.4 moles
- Mass of calcium = 16 grams

3. **Rearrange the Formula**: We can rearrange the formula to solve for molar mass (M):
\[ M = \frac{\text{mass (g)}}{n} \]

4. **Substitute the Known Values**: Now, substitute the known values into the rearranged formula:
\[ M = \frac{16 \text{ g}}{0.4 \text{ moles}} \]

5. **Calculate the Molar Mass**: Perform the calculation:
\[ M = \frac{16}{0.4} = 40 \text{ g/mol} \]

6. **Conclusion**: Therefore, the molar mass of calcium (Ca) atoms is 40 g/mol.

### Final Answer:
The molar mass of Ca atoms is **40 g/mol**.