The substance that can not be broken down by chemical means is antimony.
They are higher than water
The answer is B photosynthesis
Answer: It will take 3 days for half of a 10 g sample to decay.
Explanation:
Half-life of sample of an isotope X = 3 days
Sample decayed = 
N=
, time = t
![\ln[\frac{5}{10}]=-0.231\times t](https://tex.z-dn.net/?f=%5Cln%5B%5Cfrac%7B5%7D%7B10%7D%5D%3D-0.231%5Ctimes%20t)

t = 3 days
It will take 3 days for half of a 10 g sample to decay.