question_answer

  Baking soda is used in small amount in making bread and cake. It helps to make these soft and spongy. An aqueous solution of baking soda turns red litmus blue. It is also used in soda acid fire extinguisher. Use this information to answer the following questions (a) How does baking soda help to make cakes and bread soft and spongy? (b) How does it help in extinguishing fire? (c) Is the pH value of baking soda solution lower than or higher than 7?

Answer:

                  Copper vessel is tarnished due to copper oxide layer formed on its surface. Copper oxide is basic in nature. Lemon is acidic. Hence, when we rub the tarnished copper vessel with lemon, the basic copper oxide reacts with the acid (citric acid) present in the lemon to form a salt which is washed away with water.                                                             (3)