J.R. S. answered 05/07/20
Ph.D. University Professor with 10+ years Tutoring Experience
0.25 M = 0.25 moles Ba(OH)2 / liter solution
2 mole/x liters = 0.25 moles/ 1 liter
x = 8 liters of solution is required.
NOTE: The question is asked incorrectly since adding 8 L of water would likely result in a final volume of solution greater than 8 L