B. the frogs are a limiting factor for the gnats
the frogs limit the reproduction of the gnats, and therefore with less frogs the gnat population can increase
Depending on the size of the object, that system may describe it
in terms of inches, feet, yards, chains, rods, or miles.
Answer:
chemical change
Explanation:
In chemical change , considerable amount of heat is used , hence a change in substance formed
Answer : The time taken by the reaction is 
Explanation :
The expression used for second order kinetics is:
![kt=\frac{1}{[A_t]}-\frac{1}{[A_o]}](https://tex.z-dn.net/?f=kt%3D%5Cfrac%7B1%7D%7B%5BA_t%5D%7D-%5Cfrac%7B1%7D%7B%5BA_o%5D%7D)
where,
k = rate constant = 
t = time = ?
= final concentration = 0.40 M
= initial concentration = 2.16 M
Now put all the given values in the above expression, we get:


Therefore, the time taken by the reaction is 