Answer:
4 Fe + 3 O2 = 2 Fe2O3
Explanation:
In order to balance the equation, there should be equal number of iron atoms (Fe) and oxygen atoms (O2) in Iron(III) oxide (Fe2O3).
Since there are two atoms of Oxygen in 1 oxygen molecule and 3 atoms of Oxygen in 1 Iron Oxide, the least common multiples of the total oxygen atoms which would equal each other is 6 atoms of Oxygen. This results in 3 molecules of O2 and 2 molecules of Fe2O3.
In order to balance out the amount of iron in iron oxide, you must then calculate the total iron atoms in iron oxide; since there are 2 atoms of Fe in each molecule of Iron Oxide and there is 2 molecules of Fe2O3, the total is 2*2 = 4 atoms of iron, Fe.
In order to get 4 atoms of iron from molecules of Fe, you need 4 molecules of Fe, since each molecule contains 1 Fe.
I would be difficult to remove an electron from a Noble or Inert Gas (also known as the group 8 or 0 elements). This is because they all have filled outermost shells and as such the outermost shell would be held tightly to the nucleus and as such make it difficult to remove. Examples Helium, Neon, Argon, Xenon, Krypton and Radon
Answer:
0.08 mL
Explanation:
The solution of the skin test has a concentration of 0.2% (w/v), which means that there are 0.2 g of the antigen per 100 mL of the solution. If a new solution will be done using it, then this solution will be diluted, and the mass of the antigen added must be the same in the volume taken and at the diluted solution.
The mass is the concentration (in g/mL) multiplied by the volume of the solution (in mL), so, if m is the mass, C the concentration, V the volume, 1 the initial solution, and 2 the diluted:
m1 = m2
C1*V1 = C2*V2
Where
C1 = 0.2 g/100 mL = 0.002 g/mL
V1 = ?
C2 = 0.04 mg/mL = 0.00004 g/mL
V2 = 4 mL
0.002*V1 = 0.00004*4
V1 = 0.08 mL
