题干

X、Y、Z、W是初中化学常见的元素或物质,X是一种化石燃料的主要成分,相对分子质量为16;Y是地壳中含量最多的元素.Z的原子序数为11;W在元素周期表中位于第3周期,最外层电子数为3.下列说法不正确的是(   )

A:1个X的分子中含有5个原子

B:Y的单质的化学式是O2

C:Z的氯化物是人体不可缺少的一种化合物

D:X、Y、W三种元素可以形成化合物Na2CO3

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D

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    Lost cities that have been found

    The White City

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    Canopus and Heracleion

    Modern researchers were teased by the ancient writings about the Egyptian cities Canopus and Heracleion — where Queen Cleopatra often visited. But the cities weren't found until 1992, when a search in Alexandria waters found that the two cities had been flooded for centuries. Artifacts(史前器物)showed that the cities once highly developed as a trade network, which helped researchers piece together more about the last queen of Egypt.

Machu Picchu

    A Yale professor discovered “the Lost City in the Clouds” in 1911. A combination palaces, plazas, temples and homes, Machu Picchu displays the Inca Empire at the height of its rule. The city, which was abandoned in the 16th century for unknown reasons, was hidden by the local people from the Spanish conquerors for centuries, keeping it so well preserved.

Troy

    The ancient city of Troy in Homer's The Iliad was considered a fictional setting for his characters to run wild. But in 1871, explorations in northwestern Turkey exposed nine ancient cities layered(层叠)on top of each other, the earliest dating back to about 5,000 years before. It was later determined that the sixth or seventh layer contained the lost city of Troy and that it was actually destroyed by an earthquake, not a wooden horse.