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
I believe that the number for Co2 in 220 grams is 5
Hi there! Let's solve this problem shall we!
⠀Volume = 10g
Mass = 2 mL
In this specific problem, they are asking us to find the <u><em>density </em></u>of the object. So,<u><em> using the information given to us</em></u> (volume and mass), let's solve the problem!
Now, if you remember, D = M ÷ V
So, let's fill in the blanks!
D = Our unknown value
M = 2mL
V = 10g
Here is the filled out formula:
D = M ÷ V
D = 2mL ÷ 10g
D = 5 g/mL
*Make sure you put the units for your final solution!*