Answer:
the relation of two different forms of the same substance (such as two allotropic forms of tin) that have a definite transition point and can therefore change reversibly each into the other — compare monotropy.
Answer:
Considering the half-life of 10,000 years, after 20,000 years we will have a fourth of the remaining amount.
Explanation:
The half-time is the time a radioisotope takes to decay and lose half of its mass. Therefore, we can make the following scheme to know the amount remaining after a period of time:
Time_________________ Amount
t=0_____________________x
t=10,000 years____________x/2
t=20,000 years___________x/4
During the first 10,000 years the radioisotope lost half of its mass. After 10,000 years more (which means 2 half-lives), the remaining amount also lost half of its mass. Therefore, after 20,000 years, the we will have a fourth of the initial amount.
There are 115 known elements as of today (Feb. 13, 2016)
so, 'C' is the correct answer
<span>The minimum amount of energy needed to get a chemical reaction started is called the activation energy.
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