A milkman adds a very small amount of baking soda to fresh milk. (A52)

a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?

b) Why does this milk take a long time to set as curd?

a. He shifts the pH of the fresh milk from 6 to slightly alkaline because by doing this, he can keep the milk unspoiled for little more time than usual time.

b. After adding baking soda (alkaline in nature) to the milk, it changed into a base. But curd needs an acidic environment to set. Thus, this milk takes a long time to set as curd.