(a) What is produced if an acid is added to a base? (b) Why does dry HCl gas not change the colour of dry litmus paper? (c) What colour does phenolphthalein indicator turn when added to an alkali (such as sodium hydroxide)?
ChemistryClass 10ICSEAnswered 27 Mar 2026
Answer
- Salt and water is formed when acid is added to base NaOH(aq) + HCl(aq) →NaCl(aq) + H2O(l)
- Because dry HCl does not undergo dissociation to form ions because of the absence of aqueous medium. Colour of the litmus paper changes when ions are Hence it does not change the colour of litmus paper
- Phenolphthalein indicator turns pink when added to an alkali like sodium