Explanation:
To determine how much 85% boric acid concentrate you need to make 50 mL of a 10% boric acid solution, you can use the following formula:
concentrate needed (mL) = desired concentration * volume / desired strength
Plugging in the given values, you get:
concentrate needed (mL) = 10% * 50 mL / 85%
Simplifying, you get:
concentrate needed (mL) = 0.12 mL
So, you will need about 0.12 mL of 85% boric acid concentrate to make 50 mL of a 10% boric acid solution.