Welcome to the forum! What part of India are you from? I have only visited in the south (Kerala), but would like to see more of the country - and sample more of the food!
There are two options for determining the pH for stretching mozzarella (assuming that is the kind of cheese you mean). One is to use a pH meter than can read curds - something that can press into or onto the curds. The other is the old-fashioned way, by checking a little bit of curd periodically to see if it will stretch when heated. With experience, you can begin to know that it is getting into the range by the taste and smell, but first you have to find the right range.
Note that mozzarella is one of the hardest cheeses for most of us to make with consistent success. Some on this forum have mastered it, but most of us have had as many failures as successes.