Need help now Approximate half-life
Radon-222 = 4 days

A sample contains 18mg of radon-222. You estimate that this is 0.01% of the original isotope. How many half-lives have passed?

13 half-lives have passed

General formulas used in decay:  

T = duration of decay  

t 1/2 = half-life  

N₀ = the number of initial radioactive atoms  

Nt = the number of radioactive atoms left after decaying during T time  

t1/2 = 4 days

Nt=18 mg (0.01% of the original isotope)

18 mg (Nt) = 0.01% No

No = the original isotope :

The duration of decay  (T) :

Half-lives passed :

they all get energy from eating other animals, dead animals to be more precise.

hienas tends to steal pray from other animals. crows and vultures tend to eat dead animals and leftovers.

hope it ,

bioteacher101