Answer:
A = 679.2955 ppm
Explanation:
In this case, we already know that 64Cu has a half life of 12.7 hours. The expression to use to calculate the remaining solution is:
A = A₀ e^-kt
This is the expression to use. We have time, A₀, but we do not have k. This value is calculated with the following expression:
k = ln2 / t₁/₂
Replacing the given data we have:
k = ln2 / 12.7
k = 0.0546
Now, let's get the concentration of Cu:
A = 845 e^(-0.0546*4)
A = 845 e^(-0.2183)
A = 845 * 0.8039
A = 679.2955 ppm
This would be the concentration after 4 hours
The density of the compound is 4.64 g/
.
Explanation:
Sodium chloride crystallize as FCC face centered cubic structure. It consist of four atoms of NaCl. So the unknown compound which crytallizes like NaCl wil have volume as:
radius in fcc is calculated as
= 4r
putting the value where a is length of the edge.
= 651.9 = 4r so r= 162.98 pm
volume is calculated by the formula:
π
putting the values,
x 3.14 x (
)^3
= 4.25X 10 ^-24
1.7 X 
= volume of the fcc cell.
mass of the substance = 4 x 120 x 1.6605 x 10^(-24) g/u) (as it contains four atoms)
= 7.9x
density = 
putting the values
density = 
density = 4.64 g/
Answer: Option (6) is the correct answer.
Explanation:
Lattice energy is described as the energy released when formation of 1 mole of an ionic compound occurs due to the combination of its constituent ions.
Also, lattice energy is inversely proportional to the distance between the cation and anion. And, when we move down a group then there occurs an increase in the atomic radii of the atoms.
This means that smaller is the ionic distance between the cation and anion, more will be the lattice energy between the atoms.
Therefore, order from weakest to strongest lattice energy (most positive to most negative) for the given compounds is as follows.
barium chloride < strontium chloride < calcium chloride < magnesium chloride
Answer: 0.635 M
Explanation:
Molarity : It is defined as the number of moles of solute present per liter of the solution.
Formula used :
where,
n= Moles=
= volume of solution = 150 ml
as 1 mole of 
gives 3 moles of 
ions
Thus molarity of = 
Molarity of = 0.635 M
Answer:
T½ = 16hours
Explanation:
Final mass (N) = 10g
Initial mass (No) = 20g
Time (t) = 16hours
T½ = ?
T½ = In2 / λ
But λ = ?
In(N/No) = -λt
In(10/20) = -(λ * 16)
In(0.5) = -16λ
-0.693 = -16λ
λ = 0.693 / 16
λ = 0.0433
Note : λ is known as the disintegration constant
T½ = In2 / λ
T½ = 0.693 / 0.0433
T½ = 16hours
The half-life of the sample is 16hours
