See the book of RC Mukherjee's Chemistry book isn't available a Legal copy. So if you get any then also you will get an pirated version of the books pdf.

I would recommend you to go for a Physical Copy if possible because the physical copy will help you much better during problem solving. Now if you still want to download the soft copy then you can go for the different channels in Telegram and different sources on google available in order to download the book.

Goodnight :-)