Question

In what ph value we called strong acid and strong base

Answer 1

The pH at the equivalence point is 7.0 because the solution only contains water and a salt that is neutral. Since neither H+ nor OH- molecules remain in the solution, we can conclude that at the equivalence point of a strong acid - strong base reaction, the pH is always equal to 7.0.

Answer 2

ph value 1 to 5 we called strong acid.
ph value 9 to 14 we called strong base.