12 October 2026: geography, history, economics and SI quiz

South of the Equator and east of Greenwich — S identifies the southern side of the Equator; E identifies the eastern side of the Prime Meridian.

Equator — Latitude uses the Equator as its zero reference. The Prime Meridian is the zero reference for longitude.

It remains undeciphered — NCERT identifies the Harappan script as undeciphered, so precise translations should not be presented as settled facts.

2600–1900 BCE — NCERT labels approximately 2600–1900 BCE as the Mature Harappan phase; this is not the entire span of all associated settlement history.

₹60 — Value added is sale value minus intermediate input value: ₹90 − ₹30 = ₹60. The numbers form an original teaching example.

The intermediate value is already included in the final good — The final good incorporates its inputs’ value. Counting that input again produces double counting.

Secondary — Processing a natural product into another manufactured form is a secondary-sector activity.

Secondary sector and private ownership — Secondary describes the activity, while private describes ownership. NCERT treats these as different classification systems.

Amount of substance — BIPM pairs amount of substance with mole, symbol mol. Mass uses kilogram.

Kelvin, K — BIPM lists kelvin with symbol K as the base unit for thermodynamic temperature.