Article: As of 2007, the total installed capacity of solar hot water systems is approximately 154 thermal gigawatt (GWth). China is the world leader in their deployment with 70 GWth installed as of 2006 and a long-term goal of 210 GWth by 2020. Israel and Cyprus are the per capita leaders in the use of solar hot water systems with over 90% of homes using them. In the United States, Canada and Australia heating swimming pools is the dominant application of solar hot water with an installed capacity of 18 GWth as of 2005.

Question: What was the total capacity of solar hot water systems in 2007 in gigawatts?
Ans: 154

Article: Sixteen was held to be the minimum permissible age in the 1988 Supreme Court decision of Thompson v. Oklahoma. The Court, considering the case Roper v. Simmons in March 2005, found the execution of juvenile offenders unconstitutional by a 54 margin, effectively raising the minimum permissible age to 18. State laws have not been updated to conform with this decision. In the American legal system, unconstitutional laws do not need to be repealed; instead, they are held to be unenforceable. (See also List of juvenile offenders executed in the United States)

Question: According to Thompson v. Oklahoma, what was the youngest age at which a person might be executed?
Ans: Sixteen

Article: In addition to Virginia and Confederate government offices and hospitals, a railroad hub, and one of the South's largest slave markets, Richmond had the largest factory in the Confederacy, the Tredegar Iron Works, which turned out artillery and other munitions, including the 723 tons of armor plating that covered the CSS Virginia, the world's first ironclad used in war, as well as much of the Confederates' heavy ordnance machinery. The Confederate Congress shared quarters with the Virginia General Assembly in the Virginia State Capitol, with the Confederacy's executive mansion, the "White House of the Confederacy", located two blocks away. The Seven Days Battles followed in late June and early July 1862, during which Union General McClellan threatened to take Richmond but ultimately failed.

Question: Who commanded the Union armies during the Seven Days Battles?
Ans: McClellan

Article: Kolmas writes that, as the Mongol presence in Tibet increased, culminating in the conquest of Tibet by a Mongol leader in 1642, the Ming emperors "viewed with apparent unconcern these developments in Tibet." He adds that the Ming court's lack of concern for Tibet was one of the reasons why the Mongols pounced on the chance to reclaim their old vassal of Tibet and "fill once more the political vacuum in that country." On the mass Mongol conversion to Tibetan Buddhism under Altan Khan, Laird writes that "the Chinese watched these developments with interest, though few Chinese ever became devout Tibetan Buddhists."

Question: What were the Mongols trying to reclaim?
Ans:
their old vassal of Tibet