Answer:
% = 76.75%
Explanation:
To solve this problem, we just need to use the expressions of half life and it's relation with the concentration or mass of a compound. That expression is the following:
A = A₀ e^(-kt) (1)
Where:
A and A₀: concentrations or mass of the compounds, (final and initial)
k: constant decay of the compound
t: given time
Now to get the value of k, we should use the following expression:
k = ln2 / t₁/₂ (2)
You should note that this expression is valid when the reaction is of order 1 or first order. In this kind of exercises, we can assume it's a first order because we are not using the isotope for a reaction.
Now, let's calculate k:
k = ln2 / 956.3
k = 7.25x10⁻⁴ d⁻¹
With this value, we just replace it in (1) to get the final mass of the isotope. The given time is 1 year or 365 days so:
A = 250 e^(-7.25x10⁻⁴ * 365)
A = 250 e^(-0.7675)
A = 191.87 g
However, the question is the percentage left after 1 year so:
% = (191.87 / 250) * 100
<h2>
% = 76.75%</h2><h2>
And this is the % of isotope after 1 year</h2>
Answer: The mass density is 1166.36 
.
Explanation:
Given: Weight of sample in air 
= 500 N
Weight of sample in alcohol 
= 200 N
Specific gravity = 0.7 = 
Formula used to calculate Buoyant force is as follows.
Hence, volume of the material is calculated as follows.
where,
= Buoyant force
= specific gravity
g = acceleration due to gravity = 9.81
Substitute the values into above formula.
Now, mass of the material is calculated as follows.
Therefore, density of the material or mass density is as follows.
Thus, we can conclude that the mass density is 1166.36 .
I think it might be nitride
Answer: if your having trouble with math there is a app called photo-math just snap a quick pic of your problem and they will give you an answer
Explanation:
