The Law of Conservation of Energy states that, within a closed system, the total amount of energy remains constant. However, energy may change from kinetic to potential and vice versa. The total energy will not have changed. <span>Enthalpy is a measure of the amount of energy that exists in a system at constant pressure. </span>
Answer:
0.9715 Fraction of Pu-239 will be remain after 1000 years.
Explanation:
Where:
= decay constant
=concentration left after time t
= Half life of the sample
Half life of Pu-239 = 
[
![\lambda =\frac{0.693}{24,000 y}=2.8875\times 10^{-5} y^{-1]](https://tex.z-dn.net/?f=%5Clambda%20%3D%5Cfrac%7B0.693%7D%7B24%2C000%20y%7D%3D2.8875%5Ctimes%2010%5E%7B-5%7D%20y%5E%7B-1%5D)
Let us say amount present of Pu-239 today = 
A = ?
![A=x\times e^{-2.8875\times 10^{-5} y^{-1]\times 1000 y}](https://tex.z-dn.net/?f=A%3Dx%5Ctimes%20e%5E%7B-2.8875%5Ctimes%2010%5E%7B-5%7D%20y%5E%7B-1%5D%5Ctimes%201000%20y%7D)
0.9715 Fraction of Pu-239 will be remain after 1000 years.
Q1. Chemical, Physical, Physical, Physical
(l am not 100% sure about the 4th answer)
Q2. All of the above
<span>there are a number of animals that eat frogs that will die off, then the animals that eat them will go hungry, and their populations will die off as well. This would just keep going up the food chain. Essentially, the loss of the frogs could have deep, reverberating effects that we may not grasp until it’s too late.</span>
Answer:
21 years
% of parent isotope remaining before safe
6.25%
Explanation:
