Q1. With reference to Indian Standard Time (IST), which one of the following statements is correct?

(a) IST is maintained by the India Meteorological Department and is fixed at UTC + 6 hours.

(b) IST is based on the 82°30′ E longitude, while the CSIR-National Physical Laboratory maintains India's official national time standard.

(c) IST is determined by the longitude passing through the easternmost point of India to minimise the difference between solar time and standard time.

(d) The use of IST for official purposes is optional for private-sector entities because legal metrology regulations apply only to government departments.

Answer: (b)

Explanation:

• (b) is correct: IST corresponds to UTC + 5:30 and is based on the 82°30′ E meridian, near Mirzapur, Uttar Pradesh. The CSIR-National Physical Laboratory (NPL), New Delhi maintains India's national time standard.
• (a) is incorrect: The national time standard is maintained by NPL, not the India Meteorological Department.
• (c) is incorrect: The standard meridian was selected as a reference for a national standard time; it is not simply the easternmost longitude.
• (d) is incorrect: The notified rules seek to establish IST as the official reference for specified legal, administrative, commercial and official purposes.