A rock contains a radioactive isotope that decays to half of its original amount in 5 million years. When this rock formed, it was made up of 100%
of the radioactive isotope, and 0% of the new element that it decays
If you find this rock and analyze it, and find that it contains only 50% of the
radioactive isotope and 50% of the new element, how old must this rock
be? *

1) 2.5 millon years

2) 10 million years

3) 5 million years

4) 15 million years

the national environmental policy act (nepa) is a united states environmental law that promotes the enhancement of the environment and established the president's council on environmental quality (ceq). the law was enacted on january 1, 1970. to date, more than 100 nations around the world have enacted national environmental policies modeled after nepa.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

i don’t no. suiopgohjk

allowed for the prediction of the properties of missing elements.