Problem: Many minerals provide pigments which have been used in green paints and dyes over the centuries. Pigments, in this case, are minerals which reflect the color green, rather that emitting it through luminescent or phosphorescent qualities. The large number of green pigments makes it impossible to mention them all. Among the more notable green minerals, however is the emerald, which is colored green by trace amounts of chromium and sometimes vanadium. Chromium(III) oxide (Cr2O3), is called chrome green, also called viridian or institutional green when used as a pigment. For many years, the source of amazonite's color was a mystery. Widely thought to have been due to copper because copper compounds often have blue and green colors, the blue-green color is likely to be derived from small quantities of lead and water in the feldspar. Copper is the source of the green color in malachite pigments, chemically known as basic copper(II) carbonate.
What is the source of the green color in malachite pigments?
---
Answer: Copper

Problem: In addition to these popular examples of house, there has also been a reunification of contemporary house and its roots. Many hip hop and R&B artists also turn to house music to add a mass appeal to the music they produce.
Why do many hip hop and R&B artists turn to roots?
---
Answer: unanswerable

Problem: Critics noted in 2013 that Tom Wheeler, the head of the FCC, which has to approve the deal, is the former head of both the largest cable lobbying organization, the National Cable & Telecommunications Association, and as largest wireless lobby, CTIA The Wireless Association. According to Politico, Comcast "donated to almost every member of Congress who has a hand in regulating it." The US Senate Judiciary Committee held a hearing on the deal on April 9, 2014. The House Judiciary Committee planned its own hearing. On March 6, 2014 the United States Department of Justice Antitrust Division confirmed it was investigating the deal. In March 2014, the division's chairman, William Baer, recused himself because he was involved in a prior Comcast NBCUniversal acquisition. Several states' attorneys general have announced support for the federal investigation. On April 24, 2015, Jonathan Sallet, general counsel of the F.C.C., said that he was going to recommend a hearing before an administrative law judge, equivalent to a collapse of the deal.
When was Tom Wheeler the head of the CTIA?
---
Answer:
unanswerable