Question

The number of formula units of calcium fluoride CaF\(_2\) present in 146.4 g of CaF\(_2\) are (molar mass of CaF\(_2\) is 78.08 g/mol)

• A. \(1.129\times 10^{24}\) CaF\(_2\)
• B. \(1.146\times 10^{24}\) CaF\(_2\)
• C. \(7.808\times 10^{24}\) CaF\(_2\)
• D. \(1.877\times 10^{24}\) CaF\(_2\)

Hint:

Formula units = moles \(\times\) Avogadro number \(N_A\).

Answer 1

The Correct Option is A

Step 1: Calculate number of moles.
\[ n = \frac{\text{mass}}{\text{molar mass}} = \frac{146.4}{78.08} \approx 1.875 \text{ mol} \]
Step 2: Convert moles into number of formula units.
\[ N = nN_A = 1.875 \times 6.022\times 10^{23} \approx 1.129\times 10^{24} \]
Step 3: Match with options.
Thus the correct option is (A).
Final Answer:
\[ \boxed{1.129\times 10^{24}} \]