(3) Turmeric and phenolphthaleinare indicators for detecting theacidic and basic nature of asubstance, respectively. Dilute HClis acidic in nature, so when it isadded to the test tube A, the colourof turmeric does not change. This isbecause the colour of turmericremains yellow in acidic mediumwhile it turns red on coming incontact with a basic substance. Test tube B contains a solution ofphenolphthalein. It gives pinkcolour on reacting with bases andremains colourless in acidicsolution. So, when we add diluteHCl to the test tube B, the solutionwould remain colourless.