Answer: Hydrogen ion concentration of the lake is 
Explanation:
pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration. Acids have pH ranging from 1 to 6.9 and bases have pH ranging from 7.1 to 14.
To calculate the pH of the solution, we use the equation:
We are given:
pH = 4.0
Putting values in above equation, we get:
![[H^+]=10^{-4.0}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D10%5E%7B-4.0%7D)
![[H^+]=10^{-4}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D10%5E%7B-4%7D)
Thus hydrogen ion concentration of the lake is 
Answer:
D.
Explanation:
Inverse and proportional means as one goes up the other goes up or if one goes down the other goes down.
- Hope that helped! Please let me know if you need further explanation.