Final answer:
In a 2% potassium solution, there are 0.02 grams of potassium per milliliter. In the entire 400 mL, there are 8 grams of potassium.
Step-by-step explanation:
To find the grams of potassium per milliliter and in the entire 400 mL, we need to calculate the amount of potassium in the solution. Since we have a 2% solution, this means that for every 100 mL, there are 2 grams of potassium. Therefore, in 1 mL, there are 0.02 grams of potassium.
To find the grams of potassium in the entire 400 mL, we can multiply the grams per milliliter by the total volume, which gives us 0.02 grams/mL * 400 mL = 8 grams.