False
Explanation:
Carbon atoms are found in hydrocarbons, naturally occurring compound with carbon and hydrogen, but there are molecules in nature that contain beside carbon and hydrogen, oxygen and nitrogen too. In this compounds there are carbon-oxygen and carbon-nitrogen covalent bonds.
Bellow you may see the chemical structure of adrenaline, a hormon found in the human body, were the oxygen (red) and nitrogen (blue) are bonded to carbon.
Learn more about:
structure of organic compounds
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It might change because of the amout of rain that fell in the year and the melting of ice which allows the water amount to increase
<u>Answer:</u> The amount of Iodine-131 remain after 39 days is 0.278 grams
<u>Explanation:</u>
The equation used to calculate rate constant from given half life for first order kinetics:

where,
= half life of the reaction = 8.04 days
Putting values in above equation, we get:

Rate law expression for first order kinetics is given by the equation:
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant = 
t = time taken for decay process = 39 days
= initial amount of the sample = 8.0 grams
[A] = amount left after decay process = ?
Putting values in above equation, we get:
![0.0862=\frac{2.303}{39}\log\frac{8.0}{[A]}](https://tex.z-dn.net/?f=0.0862%3D%5Cfrac%7B2.303%7D%7B39%7D%5Clog%5Cfrac%7B8.0%7D%7B%5BA%5D%7D)
![[A]=0.278g](https://tex.z-dn.net/?f=%5BA%5D%3D0.278g)
Hence, the amount of Iodine-131 remain after 39 days is 0.278 grams