The number of formula units of calcium fluoride `CaF_(2)` present in 146.4 g of `CaF_(2)` (The molar mass of `CaF_(2)` is `78.08` g/mol) is

Options

A. `1.129 xx 10^(24) CaF_(2)`
B. `1.146 xx 10^(24) CaF_(2)`
C. `7.808 xx 10^(24) CaF_(2)`
D. `1.877 xx 10^(24) CaF_(2)`

Explanation

To find the number of formula units of calcium fluoride (CaF₂) present in 146.4 g of CaF₂, we can follow these steps:

### Step 1: Calculate the number of moles of CaF₂
To find the number of moles, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]
Given:
- Mass of CaF₂ = 146.4 g
- Molar mass of CaF₂ = 78.08 g/mol

Substituting the values:
\[ \text{Number of moles} = \frac{146.4 \, \text{g}}{78.08 \, \text{g/mol}} \approx 1.87 \, \text{moles} \]

### Step 2: Calculate the number of formula units
To find the number of formula units, we use Avogadro's number:
\[ \text{Number of formula units} = \text{Number of moles} \times \text{Avogadro's number} \]
Where Avogadro's number is \(6.022 \times 10^{23} \, \text{units/mol}\).

Substituting the values:
\[ \text{Number of formula units} = 1.87 \, \text{moles} \times 6.022 \times 10^{23} \, \text{units/mol} \]
Calculating this gives:
\[ \text{Number of formula units} \approx 1.12 \times 10^{24} \, \text{formula units} \]

### Final Answer
The number of formula units of calcium fluoride (CaF₂) present in 146.4 g of CaF₂ is approximately \(1.12 \times 10^{24}\) formula units.

---