Ice, water, fog/water vapor
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.
The parent isotope is cobalt-59 (see the picture below).
The mass number is 59 and atomic number is 27 of the parent isotope.
Neutron activation is the process in which atomic nucleus capture free neutron or neutrons.
Cobalt-60 is produced in nuclear reactors in process of neutron activation from parent isotope cobalt-59 (see the picture below).
Atomic number (Z) is total number of protons and mass number (A) is total number of protons and neutrons in a nucleus.
Cobalt-59 and cobalt-60 are the isotopes of chemical element cobalt.
Isotopes are chemical elements with same atomic number (Z), but different mass number (different number of neutrons).
More about isotopes: brainly.com/question/364529
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