Question 4: When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

Answer: When baking soda (Sodium hydrogen carbonate) is mixed with lemon juice (citric acid), bubbles are formed. The bubbles are formed due to the evolution of carbon dioxide gas. This is a chemical change. In this change, citric acid contained in lemon juice reacts with sodium hydrogen carbonate which results in the evolution of carbon dioxide gas. Lemon juice + Baking soda → Carbon dioxide + Other substances Citric acid Sodium Hydrogen carbonate