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What happened during the Cambrian explosion?

The Cambrian explosion, otherwise known as the Cambrian radiation, occurred during the Paleozoic era. Scientists believe that various factors may have triggered the sudden change, including an increase in oxygen levels, a shift in climatic conditions and the creation of more habitable environments. Some animals that flourished during the Cambrian period were the brachiopods, arthropods, nematodes, fungi and chordates, to which the human species belongs.

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Who conquered the Roman empire?

Barbarian tribes such as the Huns, Goths and Vandals presented an aggressive military presence at Rome's borders, starting in the 4th century. Government corruption, infighting and a army that was thinned due to its huge territory led to Rome's eventual fall to these tribes.\nIn the Eastern Empire, poor leadership and a loss of military might directly influenced Constantinople's demise.

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How many wives did King Khufu have?

The Great Pyramid includes a room that early explorers named the "Queen's Chamber," according to National Geographic. Despite the name, the room is not a resting place for any of Khufu's wives. The Great Pyramid is the world's largest pyramid. It took 23 years and about 2.3 million bricks to complete. Little is known about Khufu's wives, although the BBC notes that historian Herodotus portrayed Khufu as a cruel patriarch who forced his daughter into prostitution when he needed money.

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Who invented mustard gas?

In 1886, Viktor Meyer of Germany created a mustard gas compound that had a higher purity. This compound was made using a combination of aqueous potassium sulfide and 2-chloroethanol. The resulting compound was further treated using phosphorus trichloride and thiodiglycol. This amplified the effects of the compound, causing the irritation to appear hours after exposure. The effects of Meyer's higher purity compound also took longer to recover form compared to earlier forms of mustard gas.

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Who invented the kitchen sponge?

As German scientists persisted in creating uses for polyurethane foam, they created a defective batch that had many air bubbles. The outcome resembled sea sponges, which had been used since the Middle Ages to help wash the body. Prior to that, people used rags to wash dishes.\nThe earliest polyurethane sponges were easily destroyed during dish washing due to their fragility. As the technology progressed, these sponges were designed to be more durable.

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What rights did the Magna Carta protect?

A more powerful, effective draft of the Magna Carta appeared, in 1297. Although society did not change under the rule of King John, the Magna Carta established freedom for English citizens against tyrannical governments, in the years following King John's death. The first and subsequent versions of the Magna Carta addressed numerous social issues derived from the feudal system. Poor peasants and those lower on the social ladder accused King John of treating them unfairly. They noted a strong dissociation between the King and upper class and the common man.While this point raised a key soc..

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Does Brazil celebrate a holiday in honor of Amerigo Vespucci?

Of the country's national holidays, a minority are secular. These include Independence Day and Proclamation of the Republic Day.Amerigo Vespucci, having lived more than 3 centuries before the founding of Brazil, is not a key figure in the country's history. His chief contribution was to determine that the New World was not Asia, as formerly believed. As such, his first name was adapted and applied to the Americas.

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What are some Cherokee Indian tribal symbols?

The numbers four and seven represent important roles in Cherokee ceremonies and myths. The number four represents the four cardinal directions, but also the familiar forces of the world. Seven also represents the directions, plus three more. The three additional are the Upper World, Lower World and the Middle where everyone lives and remains. Seven also stands for the seven Cherokee clans and symbolizes the utmost in sacredness.\nThe owl and cougar were believed to be the only beings to achieve this level of sacredness, so they were considered important symbols to the Cherokee. Old myths say t..

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Who invented plastic and when?

Baekeland earned his wealth from selling the first commercially successful photographic paper to George Eastman for $750,000 in 1898. This gave him the freedom that he needed to pursue his own research leading to the invention of plastic. In 1905, Baekeland discovered that combining formaldehyde and phenol resulted in an interesting material that could bind powders to one another. He named the material after himself, calling it "Bakelite." This was the first thermosetting plastic.In 1931, another type of plastic, neoprene, was invented. In 1933, polythene and Perspex were invented. Then in 193..

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Why did Europe colonize Africa?

By the latter half of the 19th century, all of Europe was occupied. There was no room left for European nations to expand. Around the same time, an interest in the exploration of Africa began to take root among wealthy British men. At first, the interest was fueled primarily by the interest of finding legendary ruins and lost cities. A few expeditions, however, produced a wealth of new found commodities. Word of the financial prospects in Africa began to spread throughout Europe, which set off a race between European nations. Envoys were sent to secure peace agreements with native tribes, who ..

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