Mass of one atom of an element is 6.64×`10^(−23)`g. This is equal to :

Options

A. 40u
B. 6.64×`10^(23)`u
C. `1/40`u
D. 6.64u

Explanation

To solve the problem, we need to find the molar mass of the element given that the mass of one atom is \(6.64 \times 10^{-23}\) grams.

### Step-by-step Solution:

1. **Identify the mass of one atom**:
The mass of one atom of the element is given as:
\[ m_{\text{atom}} = 6.64 \times 10^{-23} \text{ g} \]

2. **Use Avogadro's number**:
Avogadro's number (\(N_A\)) is the number of atoms in one mole of a substance, which is approximately:
\[ N_A = 6.02 \times 10^{23} \text{ atoms/mole} \]

3. **Calculate the mass of one mole of atoms**:
The mass of one mole of atoms can be calculated using the formula:
\[ \text{Mass of one mole} = N_A \times m_{\text{atom}} \]
Substituting the values:
\[ \text{Mass of one mole} = (6.02 \times 10^{23} \text{ atoms/mole}) \times (6.64 \times 10^{-23} \text{ g/atom}) \]

4. **Perform the multiplication**:
\[ \text{Mass of one mole} = 6.02 \times 6.64 \text{ g} \]
Calculating this gives:
\[ \text{Mass of one mole} \approx 39.93 \text{ g} \]

5. **Round off the result**:
The calculated mass can be rounded off to two decimal places:
\[ \text{Mass of one mole} \approx 40.13 \text{ g} \]

6. **Convert to atomic mass unit (u)**:
The molar mass in grams per mole is numerically equivalent to the atomic mass in atomic mass units (u). Therefore:
\[ 40.13 \text{ g/mol} = 40.13 \text{ u} \]

7. **Final Answer**:
The mass of one atom of the element is equal to \(40.13\) g/mol or \(40.13\) u.

### Conclusion:
Thus, the answer to the question is:
\[ \text{Mass of one atom of the element is equal to } 40.13 \text{ g/mol or } 40.13 \text{ u.} \]