Context and question: The production for sulfidic zinc ores produces large amounts of sulfur dioxide and cadmium vapor. Smelter slag and other residues of process also contain significant amounts of heavy metals. About 1.1 million tonnes of metallic zinc and 130 thousand tonnes of lead were mined and smelted in the Belgian towns of La Calamine and Plombieres between 1806 and 1882. The dumps of the past mining operations leach significant amounts of zinc and cadmium, and, as a result, the sediments of the Geul River contain significant amounts of heavy metals. About two thousand years ago emissions of zinc from mining and smelting totaled 10 thousand tonnes a year. After increasing 10-fold from 1850, zinc emissions peaked at 3.4 million tonnes per year in the 1980s and declined to 2.7 million tonnes in the 1990s, although a 2005 study of the Arctic troposphere found that the concentrations there did not reflect the decline. Anthropogenic and natural emissions occur at a ratio of 20 to 1.
Why does the Geul River contain no heavy metals?
Answer: unanswerable
Context and question: Most of the subcontinent was conquered by the Maurya Empire during the 4th and 3rd centuries BCE. From the 3rd century BC onwards Prakrit and Pali literature in the north and the Sangam literature in southern India started to flourish. Wootz steel originated in south India in the 3rd century BC and was exported to foreign countries. Various parts of India were ruled by numerous dynasties for the next 1,500 years, among which the Gupta Empire stands out. This period, witnessing a Hindu religious and intellectual resurgence, is known as the classical or "Golden Age of India". During this period, aspects of Indian civilization, administration, culture, and religion (Hinduism and Buddhism) spread to much of Asia, while kingdoms in southern India had maritime business links with the Roman Empire from around 77 CE. Indian cultural influence spread over many parts of Southeast Asia which led to the establishment of Indianized kingdoms in Southeast Asia (Greater India).
What was the period following 3rd century BC and extending 1500 years called?
Answer: Golden Age of India
Context and question: Romila Thapar notes that the division into Hindu-Muslim-British periods of Indian history gives too much weight to "ruling dynasties and foreign invasions", neglecting the social-economic history which often showed a strong continuity. The division into Ancient-Medieval-Modern periods overlooks the fact that the Muslim conquests occurred gradually during which time many things came and went off, while the south was never completely conquered. According to Thapar, a periodisation could also be based on "significant social and economic changes", which are not strictly related to a change of ruling powers.[note 1]
What part of India was never completely conquered?
Answer:
south