Arunachal Pradesh as compared to Gujarat in the west but the watches show the same time

The sun rises two hours earlier in Arunachal Pradesh as compared to Gujarat in the west but the watches show the same time. How does this happen? 

Answer: The earth in its rotation covers a distance of 1° longitude in 4 minutes. The places located on different longitudes have different local times. 

To keep uniform system of time, the world has been divided into 24 times zones. India has a longitudinal extent of 30 from Arunachal (east) Pradesh to Western Gujarat. 

It accounts for a time difference of 2 hours. However to keep standard time across the country, 82½° E, central longitude of India, is selected as standard

meridian and local time is IST of whole country.