Answer:-6
Step-by-step explanation:
simple math
1week = 7days so
4weeks = 28 days
So 28 x 640 = 17920
1000grams = 1kg
17920 divide 1000 =17.92
Lee uses 17.92kg in those 4weeks
Given the equation:

You know that a lab technician finds that a sample of fluid has this pH:

Then, in order to find the hydrogen ion concentration of the fluid, you need to follow these steps:
1. Substitute the pH given in the exercise into the equation:

Multiply both sides by -1:

2. Solve for:

Remember that, by definition:

In this case, you can identify that:

Hence, substituting values and simplifying, you get:

Therefore, the answer is: