In the balanced reaction
2 Fe + O₂ → 2 FeO
2 moles of iron (Fe) react with 1 mole of molecular oxygen (O₂) to produce 2 moles of iron oxide (FeO). The ratio of Fe to FeO is 1-to-1, so if one starts with 42.4 mol of Fe, one will end up with the same amount of FeO, 42.4 mol.
Look up the molar mass of Fe and O:
• Fe = 55.845 g/mol
• O = 15.999 g/mol
Then the molar mass of FeO is approximately 71.835 g/mol, and so the mass of 42.4 mol of FeO is
(42.4 mol) × (71.835 g/mol) ≈ 3050 g
The 6 angles with vertex P are:
- Angle APB
- Angle APC
- Angle APD
- Angle BPC
- Angle BPD
- Angle CPD
The letter P must be in the middle since this location is the vertex. Something like angle BPA is the same as angle APB. We can swap the order of the outer letters without any change to the angle itself. Effectively, this means each angle has two possible names.
Rory walked 2/4 of a mile more than Louise.
Plug in "8i + 15j + k" for "f", and "2i – 5j + 9k" for "e"
3(8i + 15j + k) - 2(2i – 5j + 9k)
Distribute 3 to (8i + 15j + k) & - 2 to (2i – 5j + 9k)
3(8i + 15j + k) = 24i + 45j + 3k
-2(2i - 5j + 9k) = -4i + 10j - 18k
-------------------------------------------------------------------------------------------------------------------
Simplify. Combine like terms
24i - 4i + 45j + 10j + 3k - 18k
(24i - 4i) + (45j + 10j) + (3k - 18k)
20i + 55j - 15k is your answer, or (C)
-------------------------------------------------------------------------------------------------------------------
hope this helps
