- (a) The most commonly used natural indicator is litmus and is extracted from lichens.
- (b) Aqueous solution of baking soda is bitter in taste and feels soapy on touching because it contains hydroxide ions (OH⁻).
- (c) Indicators are used to test whether a substance is acidic or basic in nature.
- (d) Indicators change their colour when added to a solution containing an acidic or basic substance.
- (e) Lemon juice, orange juice taste sour because they contain citric acid.
- (f) The solutions which do not change the colour of either blue or red litmus are called neutral solutions.
- (g) Turmeric and litmus are natural acid-base indicators.
- (h) In neutralization reaction heat is always evolved.
- (i) Salts may be acidic or basic in nature.
- (j) Chemically milk of magnesia is magnesium hydroxide and baking soda is sodium bicarbonate.
- (k) China rose indicator turns acidic solution to dark pink and basic solution to green.
- (l) The correct way of making a solution of acid in water is to add acid to water slowly with constant stirring.
Parent Tip: Review the logic above to help your child master the concept of acids bases and salts worksheet.
