The number of gram-atoms in 8 g of He are

Options

A. 2
B. `1.204 xx 10^24`
C. `3.10 xx 10^23`
D. none of these

Explanation

To find the number of gram-atoms in 8 g of helium (He), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Molar Mass of Helium**:
The molar mass of helium (He) is approximately 4 grams per mole.

2. **Calculate the Number of Moles of Helium**:
To find the number of moles (n) in 8 grams of helium, we use the formula:
\[ n = \frac{\text{Given mass}}{\text{Molar mass}} \]
Substituting the values:
\[ n = \frac{8 \, \text{g}}{4 \, \text{g/mol}} = 2 \, \text{moles} \]

3. **Use Avogadro's Number**:
Avogadro's number (approximately \(6.022 \times 10^{23}\)) tells us how many atoms are in one mole of a substance. Therefore, to find the total number of atoms in 2 moles of helium, we multiply the number of moles by Avogadro's number:
\[ \text{Number of atoms} = n \times \text{Avogadro's number} \]
\[ \text{Number of atoms} = 2 \, \text{moles} \times 6.022 \times 10^{23} \, \text{atoms/mole} = 1.2044 \times 10^{24} \, \text{atoms} \]

4. **Final Answer**:
Therefore, the number of gram-atoms in 8 grams of helium is approximately \(1.204 \times 10^{24}\) atoms.