Hi there!

We can use the following conversions to solve:
Total mass --> amount of mols --> amount of atoms (Avogadro's number)
Begin by calculating the amount of boron trifluoride in 3.61 grams:
3.61 g * (1 mol BF₃ / 67.8 g) ≈ 0.0532 mol BF₃
Use avogadro's number to convert:
0.0532 mol * 6.02× 10²³atoms / 1 mol = 3.203 × 10²² atoms
Answer:
The percentage of the daily value for saturated fat provided by one package of this food is 26.0%
Explanation:
It has been given from the preceding statement that one package of the dinner provides 5.2g out of the 20 grams recommended for daily need. This is 5.2/20 x 100 given 26.0% of the daily neded value will be provided by a plate or package of the dinner.
SrSo4 = Sr(2+) + SO4(2-)
Let’s say that the initial concentration of SrSo4 was 1. ( or we have 1 mole of this reagent).
When The reaction occurs part of SrSo4is dissociated. And we get X mole Sr(2+) and So4(2-).
Ksp=[Sr(2+)]*[SO4(2-)]
X^2=3.2*10^-7
X=5.6*10^-4
Missing question: Express the salt concentration in kg/m³.
Answer is: the salt concentration is 9.8 kg/m³.
m(NaCl) = 9.8 g ÷ 1000 g/kg.
m(NaCl) = 0.0098 kg.
V(solution) = 1 L = 1 dm³.
V(solution) = 1 dm³ ÷ 1000 dm³/m³.
V(solution) = 0.001 m³.
d(solution) = m(NaCl) ÷ V(solution).
d(solution) = 0.0098 kg ÷ 0.001 m³.
d(solution) = 9.8 kg/m³.
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