They separate because of different densities.
Answer:
![[I_2]=[Br]=0.31M](https://tex.z-dn.net/?f=%5BI_2%5D%3D%5BBr%5D%3D0.31M)
Explanation:
Hello there!
In this case, according to the given information, it is possible for us to set up the following chemical equation at equilibrium:

Now, we can set up the equilibrium expression in terms of x (reaction extent) whereas the initial concentration of both iodine and bromine is 0.5mol/0.250L=2.0M:
![K=\frac{[IBr]^2}{[I_2][Br_2]} \\\\1.2x10^2=\frac{(2x)^2}{(2.0-x)^2}](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5BIBr%5D%5E2%7D%7B%5BI_2%5D%5BBr_2%5D%7D%20%5C%5C%5C%5C1.2x10%5E2%3D%5Cfrac%7B%282x%29%5E2%7D%7B%282.0-x%29%5E2%7D)
Thus, we solve for x as show below:

Therefore, the concentrations of both bromine and iodine are:
![[I_2]=[Br]=2.0M-1.69M=0.31M](https://tex.z-dn.net/?f=%5BI_2%5D%3D%5BBr%5D%3D2.0M-1.69M%3D0.31M)
Regards!
Silicon dioxide is SiO2. Silicon has 4 valence electrons, while each oxygen has 6 valence electrons. This can be shown as
** * *
** O * * Si * * O **
* * **
At points where there is one valence electron, represented by a lone *, the electrons will be 'shared' between the atoms. This will make silicon dioxide appear as
** *--------------- *
** O *--* Si * ------ * O **
*------- * **
, as the lines with no arrows indicate that each electron moves between the atoms, and does not stay with one forever.
For this problem we can use half-life formula and radioactive decay formula.
Half-life formula,
t1/2 = ln 2 / λ
where, t1/2 is half-life and λ is radioactive decay constant.
t1/2 = 8.04 days
Hence,
8.04 days = ln 2 / λ
λ = ln 2 / 8.04 days
Radioactive decay law,
Nt = No e∧(-λt)
where, Nt is amount of compound at t time, No is amount of compound at t = 0 time, t is time taken to decay and λ is radioactive decay constant.
Nt = ?
No = 1.53 mg
λ = ln 2 / 8.04 days = 0.693 / 8.04 days
t = 13.0 days
By substituting,
Nt = 1.53 mg e∧((-0.693/8.04 days) x 13.0 days))
Nt = 0.4989 mg = 0.0.499 mg
Hence, mass of remaining sample after 13.0 days = 0.499 mg
The answer is "e"