Answer:
3.9 billion years
Explanation:
The half-life of potassium-40 is the time it takes for half of it to decay.
After one half-life, half of the original amount will remain.
After a second half-life, half of that amount will remain, and so on.
We can construct a table as follows:

We see that the mass will drop to 10 g after three half-lives.
1 half-life = 1.3 billion years
3 half-lives = 3.9 billion years
Answer:
False
True
False
True
True (i think)
False
False
False
True
True
(i think they're all right but check again)
Answer:
B. non-competitive
Explanation:
As opposed as competitive inhibition, the non-competitive one does not bind with the active region of the enzyme. However, it does reduce the efficiency of the reaction because it changes the protein structure, making it unavailable for substrate.
Reversibility is related to the possibility of the reaction to be undone. If the bond is covalent, the enzyme will not return to its active state, so that would be a non-reversible bind.
ecosystem:
Living and Nonliving Things in the Ecosystem. Ecosystems -- biological communities -- include living organisms like animals, plants, insects and bacteria, as well as nonliving components like rocks, soil, water and sunlight.
The organ that is important in processing substances after being absorbed during digestion is the liver.