Answer:
a. 100 mg
b. 3.18×10²¹ atoms of F
Explanation:
Let's determine the moles of Na₂PO₃F that represents 0.76 g of compound
0.76 g . 1mol / 143.95 g = 0.00528 moles
1 mol of Na₂PO₃F has 2 moles of Na, 1 mol of P, 3 moles of O, 1 mol of F
Then, 0.00528 moles of Na₂PO₃F must have 0.00528 moles of F
Look that ratio is 1:1
Let's convert the moles to mass (g), and then from g to mg
0.00528 mol . 18.99 g/1mol = 0.100 g
0.1 g . 1000 mg/1g = 100 mg
Let's calculate the number of atoms:
1 mol has 6.02×10²³ atoms
Then, 0.00528 moles may have (0.00528 . 6.02×10²³) /1 = 3.18×10²¹ atoms
