Why 82°30'E has been selected as the Standard Meridian of India

Why 82°30'E has been selected as the

Standard Meridian of India? 

Answer: India lies to the east of the Prime Meridian between 68°7’ to 97°25’E Longitude which makes a vast longitudinal extent of India about 30°.

This accounts for a time lag of two hours in local time between its eastern (Arunachal PRadesh) and western extents(Gujarat). 

82°30' E meridian divides the two hour lag from west to east into one hour by passing through mirzapur in Uttar pradesh. This meridian has been accepted as the Indian Standard Time (IST) throughout the country.