A milkman adds a very small amount of baking soda to fresh milk.
(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) When the milk is made more alkaline by adding a base to it, it is basically done to prevent it  for more time to turning to curd. That’s why milkman shifts the $pH$ of fresh milk to slightly alkaline by adding a very small amount of baking soda to it as baking soda is alkaline in nature and it neutralizes the acidic nature of milk.