QUES: There are also open compression formats like Opus and Vorbis that are available free of charge and without any known patent restrictions. Some of the newer audio compression formats, such as AAC, WMA Pro and Vorbis, are free of some limitations inherent to the MP3 format that cannot be overcome by any MP3 encoder.
Being open formats means that Opus and Vorbis can be used without what?

ANS: any known patent restrictions

QUES: The 1469 marriage of Isabella I of Castile and Ferdinand II of Aragon and the 1479 death of John II of Aragon led to the creation of modern-day Spain. In 1492, Granada was captured from the Moors, thereby completing the Reconquista. Portugal had during the 15th century – particularly under Henry the Navigator – gradually explored the coast of Africa, and in 1498, Vasco da Gama found the sea route to India. The Spanish monarchs met the Portuguese challenge by financing the expedition of Christopher Columbus to find a western sea route to India, leading to the discovery of the Americas in 1492.
The release of which city finalized the Reconquista?

ANS: unanswerable

QUES: Mining was important in Thuringia since the later Middle Ages, especially within the mining towns of the Thuringian Forest such as Schmalkalden, Suhl and Ilmenau. Following the industrial revolution, the old iron, copper and silver mines declined because the competition from imported metal was too strong. On the other hand, the late 19th century brought new types of mines to Thuringia: the lignite surface mining around Meuselwitz near Altenburg in the east of the Land started in the 1870s, and two potash mining districts were established around 1900. These are the Südharzrevier in the north of the state, between Bischofferode in the west and Roßleben in the east with Sondershausen at its centre, and the Werrarevier on the Hessian border around Vacha and Bad Salzungen in the west. Together, they accounted for a significant part of the world's potash production in the mid-20th century. After the reunification, the Südharzrevier was abandoned, whereas K+S took over the mines in the Werrarevier. Between 1950 and 1990, uranium mining was also important to cover the Soviet Union's need for this metal. The centre was Ronneburg near Gera in eastern Thuringia and the operating company Wismut was under direct Soviet control.
Which towns in Thuringia are falsely known as mining towns?

ANS: unanswerable

QUES: In the Middle Ages, several powerful Somali empires dominated the regional trade including the Ajuran Sultanate, which excelled in hydraulic engineering and fortress building, the Sultanate of Adal, whose general Ahmad ibn Ibrahim al-Ghazi (Ahmed Gurey) was the first commander to use cannon warfare on the continent during Adal's conquest of the Ethiopian Empire, and the Sultanate of the Geledi, whose military dominance forced governors of the Omani empire north of the city of Lamu to pay tribute to the Somali Sultan Ahmed Yusuf.
What Somali leader received tribute from the Omani empire?

ANS:
Sultan Ahmed Yusuf