77.78 grams
<h3>
Further explanation</h3>
<u>Given:</u>
A chemist has 100g of 25% acid solution.
<u>Question:</u>
How much of these solution he needs to drain and replace with 70% acid solution to obtain 100g of 60% acid solution?
<u>The Process:</u>
We will solve the chemical problem of mixed concentration. A chemist wants to get an acid solution with new concentrations. He needs to drain the initial solution and replace it with another concentration of an acid solution.
- Let x grams 25% acid solution mixed with y grams of 70% acid solution to obtain 100g of 60% acid solution.
- Remember, a chemist first had 100 grams of acid solution. Then the part he needs to drain is (100 - x) grams.
Let's arrange the equations.


We work on Equation-2 first.

Substitute Equation-1 to Equation-2.




Therefore, 
Thus, he needs to drain 
<h3>Learn more</h3>
- How many liters of the 50% solution and how many liters of the 90% solution will be used? brainly.com/question/13034221
- Calculating the pH value of weak base brainly.com/question/9040743
- About electrolyte and nonelectrolyte solutions brainly.com/question/5404753
Keywords: a chemist, has 100g, 25% acid solution, how much, he needs, to drain, and replace with, 70%, to obtain, 60%, mixed, initial, new