Question

U r provided with three test tube containing distilled water an acid and a base solution

Answer 1

first take the blue litmus paper and dip it in the first testube if the litmus paper is still blue its distilled water l now dip the litmus paper in second test tube the litmus paper turns red so it is an acid  take the red litmus paper and dip it in the third testube  and it turns blue again so its a base
therefore
1st solution is neutral so its disttlled water
2nd solution is an acid 
3rd solution is base
HOPE THIS HELPS YOU