I'm going to go with Physical.
The least dense layer of the earth is the crust.
Answer: half life
Explanation: Radioactive decay follows first order kinetics and the time required for the decay of a radioactive material is calculated as follows:

t= time required
k= disintegration constant
x= amount of substance left after time t
a= initial amount of substance
when one half of the sample is decayed, one half of the sample remains and t can be represented as 
at
, 


3
Species
Genetic diversity
Ecosystem diversity
Answer: 1.) His action is not justified because he could have done something else like talking with someone.
2.) Some of the negative consequences could be Mr. King could lose his job or worse not be able to teach again.
3.) Some other options were having him retake the test or talking to the head of the school, or many other things.