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:
2. 14
Explanation:
To form Br₂ bond, a total of 14 electrons are needed.
Bromine is an element in the 7th group on the periodic table. It has 7 valence electrons.
- In forming the bromine gas, the two atoms of bromine shares 7 electrons each.
- These electrons are from their outermost shell.
- The outermost shell is the valence shell.
- So, two atoms donating 7 electrons gives 14 electrons.
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