NCERT Solutions for Class 10th Science
Chapter 2. Acids, Bases and Salts
- There are some substances whose odour changes in acidic or basic media. These are called olfactory indicators.
- Vanilla, onion and clove, can be used as olfactory indicators.
- The metal combines with the remaining part of the acid and forms a compound called a salt.
- Limestone, chalk and marble are different forms of calcium carbonate.
- The reaction between an acid and a base to give a salt and water is
known as a neutralisation reaction.
- Metallic oxides react with acids to give salts and water, similar to the
reaction of a base with an acid, metallic oxides are said to be basic oxides.
- All acids produce hydrogen ions, H+(aq), in solution.
- All bases produce OH–(aq), in solution.
- The pH of a neutral solution is 7.
- Values less than 7 on the pH scale represent an acidic solution.
- PH of rain water is less than 5.6, it is called acid rain.
- Tooth decay starts when the pH of the mouth is lower than 5.5.
- Salts of a strong acid and a strong base are neutral with pH value of 7.
- The salt formed by the combination of hydrochloric acid and
sodium hydroxide solution is called sodium chloride.
- Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is
called rock salt
- When electricity is passed through an aqueous solution of sodium
chloride (called brine).
- The baking soda commonly used in the kitchen for making tasty crispy pakoras.
- On heating gypsum at 373 K, it loses water molecules and becomes
calcium sulphate hemihydrate. This is called Plaster of Paris.