We know this because of the discovery of fossils and bones. We can find out roughly when they existed because of carbon dating.
The answer for this question is B) Ionization and Dissociation because Dissociation happens, charged particles form (ions), and since the ions didn't exist before the substance was dissolved, this process is called IONIZATION. It is the process that involves the formation of ions, a conversion of a substance into ions.
Answer:
= 72900 years
Explanation:
- The half-life is the time taken by a radioactive material to decay by half the original amount.
- The half-life of plutonium-239 is 24300 years which means it takes 24300 years to decay by half the original amount.
To calculate the time taken for a mass of 8 kg to decay to 1 kg we use;
New mass = Original mass x (1/2) ^n, where n is the number of half-lives
Therefore;
1 kg = 8 kg × (1/2)^n
1/8 = (1/2)^n
solving for n;
n =3
Therefore;
Time = 3 × 24300 years
= 72900 years
It will, therefore, take 72900 years for 8 kg of plutonium-239 to decay to 1 kg.
A network.. where one thing ends another begins
The water on your skin is evaporating, pulling heat with it. This is called evaporative cooling.