Sonu' s mother served a glass of hot milk before his going to school. as sonu was in a hurry he forgot to drink the milk. unfortunately his mother has also gone out. when they came back home, sonu noticed the changes in the milk, which was no more a milk, but set into a thick substance called curd.

based on this situation answer the following questions:

a. what is this process of setting milk into curd known as? is this a physical/chemical change?

b. is this change harmful ?

c. how does it happen?

its your choice that whether you want to answer all the 3 questions or just 2 of them.