Q. Which metal was unknown to Indus Valley Civilization?
(a) Gold
(b) Silver
(c) Copper
(d) Iron
Ans: (d) Iron
Explanation: The metal that was unknown to the Indus Valley Civilization was (d) Iron. Iron metallurgy and its widespread use came into prominence during a later period in human history, known as the Iron Age, which followed the decline of the Indus Valley Civilization. However, the Indus Valley Civilization had knowledge and use of other metals such as copper, bronze, gold, and silver. Iron became a significant metal for various purposes, including tools, weapons, and implements, in subsequent civilizations and time periods.