Question: In almost all federations the central government enjoys the powers of foreign policy and national defense as exclusive federal powers. Were this not the case a federation would not be a single sovereign state, per the UN definition. Notably, the states of Germany retain the right to act on their own behalf at an international level, a condition originally granted in exchange for the Kingdom of Bavaria's agreement to join the German Empire in 1871. Beyond this the precise division of power varies from one nation to another. The constitutions of Germany and the United States provide that all powers not specifically granted to the federal government are retained by the states. The Constitution of some countries like Canada and India, on the other hand, state that powers not explicitly granted to the provincial governments are retained by the federal government. Much like the US system, the Australian Constitution allocates to the Federal government (the Commonwealth of Australia) the power to make laws about certain specified matters which were considered too difficult for the States to manage, so that the States retain all other areas of responsibility. Under the division of powers of the European Union in the Lisbon Treaty, powers which are not either exclusively of European competence or shared between EU and state as concurrent powers are retained by the constituent states.
Is there an answer to this question: In nearly all federalism countries, central powers enjoy what?

Answer: the powers of foreign policy and national defense as exclusive federal powers

Question: The Vikings established Danelaw over much of the eastern and northern part of England with its boundary roughly stretching from London to Chester. It was an area of political and geographical control imposed by the Viking incursions which was formally agreed to by the Danish warlord, Guthrum and west-Saxon king, Alfred the Great in 886 AD. The Anglo-Saxon Chronicle recorded that London was "refounded" by Alfred the Great in 886. Archaeological research shows that this involved abandonment of Lundenwic and a revival of life and trade within the old Roman walls. London then grew slowly until about 950, after which activity increased dramatically.
Is there an answer to this question: Following the Viking invasion, when did London begin to significantly grow and expand?

Answer: about 950

Question: Shih-Shan Henry Tsai writes that the Yongle Emperor sent his eunuch Yang Sanbao into Tibet in 1413 to gain the allegiance of various Tibetan princes, while the Yongle Emperor paid a small fortune in return gifts for tributes in order to maintain the loyalty of neighboring vassal states such as Nepal and Tibet. However, Van Praag states that Tibetan rulers upheld their own separate relations with the kingdoms of Nepal and Kashmir, and at times "engaged in armed confrontation with them."
Is there an answer to this question: When did Yongle Emperor send Yang Sanbao into Tibet?

Answer: 1413

Question: Together with caesium and gold (both yellow), and osmium (bluish), copper is one of only four elemental metals with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells the energy difference between these shells is such that it corresponds to orange light. The same mechanism accounts for the yellow color of gold and caesium.
Is there an answer to this question: What color is fake copper?

Answer:
unanswerable