Question

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?

NCERT Class 10th Science Chapter 2 Acids Bases and Salts

Answer 1

He shifts the pH of the fresh milk from 6 to alkaline so that in basic form it will not spoil easily. This milk takes a long time to set as curd because the lactic acid produced reacts with the baking soda.

Answer 2

a fresh milk is acidic and it turn sour easily to become more acidic. in the presenc eof baking soda, milk become alkaline and does not turn sour easily because the alkali does not allow the milk to become more acidic
b. when the milk set to curd,the ph decrease.. the presence of alkali does not allow it to become acidic easily..hence it take long time to set as curd