Correct Option
The correct option is (c) 1 and 3 only.
Explanation
Indian Standard Time (IST) is the uniform time observed throughout India, with a time offset of UTC+05:30. It is determined based on a specific central meridian to ensure administrative convenience across the country's longitudinal expanse.
Statement-wise Analysis
- Statement 1 is Correct: The longitude of 82°30' E is officially designated as the Standard Meridian of India. It passes through Mirzapur (near Prayagraj) in Uttar Pradesh and serves as the reference for calculating time for the entire nation.
- Statement 2 is Incorrect: The local time at the Standard Meridian is applied as the standard time for the entire country, not just the northern states. Despite the significant longitudinal difference between Gujarat in the west and Arunachal Pradesh in the east (approx. 2 hours), a single time zone is maintained for national uniformity.
- Statement 3 is Correct: The Prime Meridian (0° longitude) passes through Greenwich near London. India is situated entirely in the Eastern Hemisphere, located east of the Prime Meridian. Consequently, Indian Standard Time is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT).
Key Takeaway: India follows a single time zone (IST) based on the 82°30' E longitude, which applies to the whole country and places India 5 hours and 30 minutes ahead of Greenwich.