What is the gram-formula mass of \( \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} \) ? 1. \( 248 \mathrm{~g} / \mathrm{mol} \) 2. \( 263 \mathrm{~g} / \mathrm{mol} \) 3. \( 279 \mathrm{~g} / \mathrm{mol} \) 4. 310. \( \mathrm{g} / \mathrm{mol} \)

Step 1 ：\( \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} \Rightarrow 3 \times \mathrm{Ca} + 2 \times \left(\mathrm{P} + 4\times \mathrm{O}\right) \)

Step 2 ：\( = 3 \times 40.08 + 2 \times \left(30.97 + 4 \times 16.00\right) \)

Step 3 ：\( = 3 \times 40.08 + 2 \times \left(30.97 + 64.00\right) \)

Step 4 ：\( = 120.24 + 2 \times (94.97) \)

Step 5 ：\( = 120.24 + 189.94 \)

Step 6 ：\( = 310.18 \mathrm{~g} / \mathrm{mol} \)