问题
问答题
市售脑黄金化学式为C25H51COOH，其相对分子质量为：______其中氧元素和氢元素的质量比为：______．
答案
（1）脑黄金（C25H51COOH）的相对分子质量为12×26+1×52+16×2=396．
（2）脑黄金（C25H51COOH）中氧元素和氢元素质量比为（16×2）：（1×52）=8：13．
故答案为：396；8：13．
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市售脑黄金化学式为C25H51COOH，其相对分子质量为：______其中氧元素和氢元素的质量比为：______．
（1）脑黄金（C25H51COOH）的相对分子质量为12×26+1×52+16×2=396．
（2）脑黄金（C25H51COOH）中氧元素和氢元素质量比为（16×2）：（1×52）=8：13．
故答案为：396；8：13．
| 完形填空。 | |||
| In 1955,Ray Kroc l a small restaurant in California. It 2 next to the road, so customers could drive up to the restaurant and drive away 3 . It was owned by the McDonald brothers, Dick and Mac. The McDonald brothers had developed a new idea: "drive-in" restaurant, where people can order food 4 their cars. The restaurant also 5 on the number of choices on the menu, so the cooks could make the food very 6 . The restaurant specialized in 7 hamburgers, French fries, and chocolate shakes. Ray Kroc recognized the potential of the McDonald brothers' restaurant, and he bought the rights to their idea. Mr Kroc wanted to 8 his own restaurant, and he wanted to use the brothers' family 9 . The brothers agreed, and the McDonald's restaurant chain 10 . | |||
| ( )l. A. opened ( )2. A. builds ( )3. A.easily ( )4. A. out ( )5. A. added ( )6. A. slowly ( )7. A. make ( )8. A.have ( )9. A.house ( )10. A. was born | B.visited B. built B. slowly B. from B. cut B. easily B. making B. own B. money B. came into being | C.saw C. was built C.often C.in C. added up C. quickly C.to make C.open C.right C. appeared | D.had D. building D.difficult D.inside D. cut down D. satisfyingly D.made D.run D.name D. opened |