Problem: In 1516, William IV, Duke of Bavaria, adopted the Reinheitsgebot (purity law), perhaps the oldest food-quality regulation still in use in the 21st century, according to which the only allowed ingredients of beer are water, hops and barley-malt. Beer produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century AD, beer was also being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century. The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process and greater knowledge of the results.
What was the name of the purity law that regulated beer in 1516, and is still in use today?
The answer is the following: Reinheitsgebot

Problem: Much of mandolin development revolved around the soundboard (the top). Pre-mandolin instruments were quiet instruments, strung with as many as six courses of gut strings, and were plucked with the fingers or with a quill. However, modern instruments are louder—using four courses of metal strings, which exert more pressure than the gut strings. The modern soundboard is designed to withstand the pressure of metal strings that would break earlier instruments. The soundboard comes in many shapes—but generally round or teardrop-shaped, sometimes with scrolls or other projections. There is usually one or more sound holes in the soundboard, either round, oval, or shaped like a calligraphic F (f-hole). A round or oval sound hole may be covered or bordered with decorative rosettes or purfling.
What did most of the development of the mandolin revolve around?
The answer is the following: soundboard (the top)

Problem: At the age of 21 he settled in Paris. Thereafter, during the last 18 years of his life, he gave only some 30 public performances, preferring the more intimate atmosphere of the salon. He supported himself by selling his compositions and teaching piano, for which he was in high demand. Chopin formed a friendship with Franz Liszt and was admired by many of his musical contemporaries, including Robert Schumann. In 1835 he obtained French citizenship. After a failed engagement to Maria Wodzińska, from 1837 to 1847 he maintained an often troubled relationship with the French writer George Sand. A brief and unhappy visit to Majorca with Sand in 1838–39 was one of his most productive periods of composition. In his last years, he was financially supported by his admirer Jane Stirling, who also arranged for him to visit Scotland in 1848. Through most of his life, Chopin suffered from poor health. He died in Paris in 1849, probably of tuberculosis.
What other composer did Chopin develop a friendship with?
The answer is the following: Franz Liszt

Problem: When Emperor Kammu moved the capital to Heian-kyō (Kyōto), which remained the imperial capital for the next 1,000 years, he did so not only to strengthen imperial authority but also to improve his seat of government geopolitically. Nara was abandoned after only 70 years in part due to the ascendancy of Dōkyō and the encroaching secular power of the Buddhist institutions there. Kyōto had good river access to the sea and could be reached by land routes from the eastern provinces. The early Heian period (784–967) continued Nara culture; the Heian capital was patterned on the Chinese Tang capital at Chang'an, as was Nara, but on a larger scale than Nara. Kammu endeavoured to improve the Tang-style administrative system which was in use. Known as the ritsuryō, this system attempted to recreate the Tang imperium in Japan, despite the "tremendous differences in the levels of development between the two countries". Despite the decline of the Taika-Taihō reforms, imperial government was vigorous during the early Heian period. Indeed, Kammu's avoidance of drastic reform decreased the intensity of political struggles, and he became recognized as one of Japan's most forceful emperors.
What time period was the early Heian era?
The answer is the following:
784–967