A sample of moon rock was found to contain 40 argon-40 atoms for every 5 potassium-40 atoms. The half-life of postassium-40 is 1
.25 billion years. Assuming no loss of daughter isotopes, how old is the moon rock? a) 3.75 billion years old
b) 2.5 billion years old
c) 10.5 billion years old
d) 6.75 billion years old
Half life is the time needed for a radioactive molecule to decay 50% or half of its weight. When decay, half of the radioactive parent molecule will be changed into children molecule. So, the ratio of parent: child molecule can be used to determine how many half-lives already happen. The parent molecule would be potassium-40 and the child molecule is argon-40. The number of half-live would be: parent molecule/child molecule = (1/2)^(half-live) 5/40= (1/2)^(half-live) 1/8= (1/2)^(half-live) (1/2)^3=(1/2)^(half-live) half live= 3
If the half-life is 1.25 billion years, the age of the rock would be: age= half-life count * half-life duration age= 3 * 1.25 billion years age= 3.75 billion years
Birds migrating in the winter would be a behavioral adaptation. The rest of the adaptations would be structural or physiological because they are controlled by mutations in the DNA. <span />
Active transport proteins use adenosine triphosphate (ATP), the cell's energy storage molecule, to pump glucose into the cell, either with or against the concentration gradient.
