Problem: In 1952, following a referendum, Baden, Wurttemberg-Baden, and Wurttemberg-Hohenzollern merged into Baden-Wurttemberg. In 1957, the Saar Protectorate rejoined the Federal Republic as the Saarland. German reunification in 1990, in which the German Democratic Republic (East Germany) ascended into the Federal Republic, resulted in the addition of the re-established eastern states of Brandenburg, Mecklenburg-West Pomerania (in German Mecklenburg-Vorpommern), Saxony (Sachsen), Saxony-Anhalt (Sachsen-Anhalt), and Thuringia (Thuringen), as well as the reunification of West and East Berlin into Berlin and its establishment as a full and equal state. A regional referendum in 1996 to merge Berlin with surrounding Brandenburg as "Berlin-Brandenburg" failed to reach the necessary majority vote in Brandenburg, while a majority of Berliners voted in favour of the merger.
Why did a regional referendum in 1996 to merge Berlin with surrounding Brandenburg fail?
The answer is the following: failed to reach the necessary majority vote in Brandenburg

Problem: Eritrea can be split into three ecoregions. To the east of the highlands are the hot, arid coastal plains stretching down to the southeast of the country. The cooler, more fertile highlands, reaching up to 3000m has a different habitat. Habitats here vary from the sub-tropical rainforest at Filfil Solomona to the precipitous cliffs and canyons of the southern highlands. The Afar Triangle or Danakil Depression of Eritrea is the probable location of a triple junction where three tectonic plates are pulling away from one another.The highest point of the country, Emba Soira, is located in the center of Eritrea, at 3,018 meters (9,902 ft) above sea level.
What is the probably location in Eritrea where three tectonic plates are pulling away from each other?
The answer is the following: The Afar Triangle or Danakil Depression

Problem: In recent decades, a series of inscribed graphs and pictures have been found at Neolithic sites in China, including Jiahu (c. 6500 BC), Dadiwan and Damaidi from the 6th millennium BC, and Banpo (5th millennium BC). Often these finds are accompanied by media reports that push back the purported beginnings of Chinese writing by thousands of years. However, because these marks occur singly, without any implied context, and are made crudely and simply, Qiu Xigui concluded that "we do not have any basis for stating that these constituted writing nor is there reason to conclude that they were ancestral to Shang dynasty Chinese characters." They do however demonstrate a history of sign use in the Yellow River valley during the Neolithic through to the Shang period.
What color was the famous valley during the Neolithic through to the Shang period?
The answer is the following: Yellow

Problem: Classical statistical mechanics requires the existence of h (but does not define its value). Eventually, following upon Planck's discovery, it was recognized that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the "quantum of action", now called the Planck constant. Classical physics cannot explain this fact. In many cases, such as for monochromatic light or for atoms, this quantum of action also implies that only certain energy levels are allowed, and values in between are forbidden.
What is the Planck constant formerly known as?
The answer is the following:
quantum of action