Question

why is 82.5 longitude chosen a standard meridian of india​

Answer 1

Indian Standard Time (IST) is the timeobserved throughout India, with a time offsetof UTC+05:30. India does not observe daylight saving time (DST) or other seasonal adjustments. In military and aviation time IST is designated E* ("Echo-Star").

Indian Standard Time is calculated on the basis of 82.5' E longitude, in Mirzapur(Amravati Chauraha), Uttar Pradesh, which is nearly on the corresponding longitude reference line.