Answer:
7.951 x 0²³atoms
Explanation:
Mass of Fe₃O₄ = 140g
Solution:
To find the number of oxygen atoms in iron(III) oxide, we first find the number of moles in the compound:
Number of moles =
Molar mass of Fe₃O₄ = (3x56) + (4x64) = 168 + 256 =424g/mol
Number of moles = = 0.33mole
1 mole of an atom contains 6.02 x 10²³atoms
∴number of oxygen atoms in Fe₃O₄ = 4 x 0.33 x 6.02 x 10²³atoms
= 7.951 x 0²³atoms
Answer:
2000 years
Explanation:
A radioactive molecule will continuously decay and turn into another molecule. This nature of the radioactive molecule makes them can be used to estimate the age of an object. Half-life is the unit of time needed for radioactive molecules to decay to half of its mass. The formula for the mass remaining will be:
Where
N(t)= number of the molecule remains
N0= number of molecule initially
t= time elapsed
t1/2= half time
We have all variable besides the half time, the calculation will be:
3= 6000/ (t1/2)
t1/2= 6000/3= 2000
The half-life is 2000 years