Water is found in lakes and rivers. Its purpose in nature is to hydrate animals
Hydrogen gas is not abundant in nature, but hydrogen is abundant in water. Hydrogen (bonds) help ice float. Otherwise, freezing lakes would kill animals (it actually doesn't since the ice creates a "coat" above the water").
Ammonia is nitrogen-rich molecules that plant uses to get their nitrogen. It comes from the part of the nitrogen cycle where dead plants and animals are decayed.
Carbon dioxide is what we exhale. Plants "inhale" carbon dioxide and use that for photosynthesis.
Hydrogen sulfide is emitted by volcanoes and by anaerobic (oxygen-less) decay from bacteria.
Have an awesome day! I hope this helps.
I did the test and the answer is C.
Answer:
The concentration of methyl isonitrile will become 15% of the initial value after 10.31 hrs.
Explanation:
As the data the rate constant is not given in this description, However from observing the complete question the rate constant is given as a rate constant of 5.11x10-5s-1 at 472k .
Now the ratio of two concentrations is given as

Here C/C_0 is the ratio of concentration which is given as 15% or 0.15.
k is the rate constant which is given as 
So time t is given as

So the concentration will become 15% of the initial value after 10.31 hrs.