The correct option is 2 and 3 only
Explanation
Indian Standard Time (IST) is the time observed throughout India and Sri Lanka, with a time offset of UTC+05:30. It is calculated on the basis of a specific longitude chosen to pass roughly through the center of the country to ensure a uniform time zone.
- Statement 1 is Incorrect: The Indian Standard Time is calculated on the basis of 82°30' E longitude (82.5° E), not 90° E. The 90° E meridian passes further east, through states like Assam and Meghalaya.
- Statement 2 is Correct: The Standard Meridian of India (82°30' E) passes through Mirzapur (near Prayagraj/Allahabad) in Uttar Pradesh. This meridian is taken as the standard time for the whole country. It passes through five states: Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Odisha, and Andhra Pradesh.
- Statement 3 is Correct: The Earth rotates 360° in about 24 hours, which means 15° per hour or 1° every 4 minutes. Since the Standard Meridian of India is 82°30' E, the time difference is calculated as:
82.5 × 4 minutes = 330 minutes
330 minutes = 5 hours and 30 minutes.
Since India is located east of the Prime Meridian (Greenwich), IST is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT).
Key Takeaway: Indian Standard Time is based on the 82°30' E meridian, which passes through Mirzapur, and is 5 hours 30 minutes ahead of GMT.