Question

(a) Mention the pH range within which our body works. Explain how antacids give relief from acidity. Write the name of one such antacid. 

(b) Fresh milk has a pH of 6. How does the pH will change as it turns to curd? Explain your answer. 

(c) A milkman adds a very small amount of baking soda to fresh milk. Why does this milk take a longer time to set as curd? 

(d) Mention the nature of toothpastes. How do they prevent tooth decay?

Answer 1

(a) Our stomach has pH equal to 2. Antacids neutralizes excess of acid in our body and gives relief from hyperacidity. Sodium hydrogencarbonate is one of such antacid. 

(b) pH will decrease as it turns to curd because curd is acidic due to the presence of lactic acid. 

(c) It takes longer time to set as curd as bacteria do not work well in presence of sodium hydrogencarbonate, i.e. fermentation will take place slowly. 

(d) Toothpastes are basic in nature. They neutralize the acid formed in mouth which causes tooth decay.