Radio active decay reactions follow first order rate kinetics.
a) The half life and decay constant for radio active decay reactions are related by the equation:



Where k is the decay constant
b) Finding out the decay constant for the decay of C-14 isotope:



c) Finding the age of the sample :
35 % of the radiocarbon is present currently.
The first order rate equation is,
![[A] = [A_{0}]e^{-kt}](https://tex.z-dn.net/?f=%20%5BA%5D%20%3D%20%5BA_%7B0%7D%5De%5E%7B-kt%7D%20%20%20)
![\frac{[A]}{[A_{0}]} = e^{-kt}](https://tex.z-dn.net/?f=%20%5Cfrac%7B%5BA%5D%7D%7B%5BA_%7B0%7D%5D%7D%20%3D%20e%5E%7B-kt%7D%20%20)


t = 7923 years
Therefore, age of the sample is 7923 years.
<span><span>The column of a fractional distillation apparatus should be
aligned vertical to get better separation because
the column is essentially longer. It will prevent channeling in the
column. </span>Therefore column efficiency will be higher if it is as
vertical as possible instead of tilted.<span> Distillation is a process used to separate a mixture of two (or
more) components. In a typical </span>fractional
distillation, a liquid mixture
is heated in the distilling flask and the
process begins.</span>
Independent variable: the student chooses to miss class.
dependent variable: in result of the student missing class his grade goes down.
hyposthesis: if the student misses class multiple times, then his grades will go down.
The answer is GRAINS
i realy hope this helped
Explanation:
Ca3(PO4)2 1 mole has 310.2 g
Ca3(PO4)2 4.3 × 10^-4 moles has 4.3 × 10^-4 × 310.2
= 1,333.86 × 10^-4
= 1.334 × 10^-1
OR 0.1334 g