Can you reword it im confused
Answer:
Hey!
Your answer is element A
Explanation:
Using the graph, the element A's emission of radioactive particles ends approximately after 6 years...
A HALF-LIFE IS "HALF" OF THAT TIME PERIOD!
So if the radiation goes for 6 years the half-life is 6 divided by two which gives you 3 years!
The rest however have a longer half-life...
Because they all end at 14 yrs so their half-life in 7 years!
HOPE THIS HELPS!!
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 
This would equal -1 or negative one