Activity 2.6 of the ncerttext,page21please...
NaOh solution + 2 Drops of phenolphthlalein solution - Colour Of solution is pink
On adding dilute HCL solution drop by drop to the above solution - The reaction mixture change to colourless.
Phenolphthlalin colour changes from pink to colourless as neutralisation of HCL and NaOH takes place.
On adding fre drops of NaOH to the above mixture, pink colour reappeaers because intittially the effect of base was nullified by an acid and so the colour changed to colourless but on addiction of some more base the pink colour of phenolphtalein reapperead
On adding dilute HCL solution drop by drop to the above solution - The reaction mixture change to colourless.
Phenolphthlalin colour changes from pink to colourless as neutralisation of HCL and NaOH takes place.
On adding fre drops of NaOH to the above mixture, pink colour reappeaers because intittially the effect of base was nullified by an acid and so the colour changed to colourless but on addiction of some more base the pink colour of phenolphtalein reapperead