某物质的摩尔质量为μ，密度为ρ，NA为阿伏加德罗常数，则每单位_爱下问搜题

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问题填空题

某物质的摩尔质量为μ，密度为ρ，N_A为阿伏加德罗常数，则每单位体积中这种物质所包含的分子数目是______．若这种物质的分子是一个挨一个排列的，则它的直径约为______．

答案

每个分子的质量m=

μ

NA

．单位体积的质量等于单位体积乘以密度，质量除以摩尔质量等于摩尔数，所以单位体积所含的分子数n=

ρ

μ

N_A．

将这种物质的分子是一个挨一个排列的，而且看成立方体形，则每个分子的体积为

V=

μ

ρ

•

1

NA

又V=d³，则得分子直径为 d=

3

μ

ρNA

故答案为：

ρ

μ

N_A，

3

μ

ρNA

完形填空

With a determined(坚定的) look on his face, Chicago’s Michael McCarthy held on to the banister(扶手) and climbed to the top of the Willis Tower not long ago. The Tower stands 1,451 feet tall, the      building in the US.
As he got to the last step, McCarthy      fell down, but that didn’t stop him. The 14-year-old boy finally finished climbing the 2,109 steps and arrived at the top, where he      cheers from many people.
“I just want to show people that      a kid with no legs can do it, anyone can do it,” McCarthy said.
McCarthy, who was born without legs, has to wear prosthetic legs(假肢) and use a stick to walk. But McCarthy has a strong     . He believes having a disability shouldn’t stop anyone     achieving his or her success.
He has been in a special school     he was four. When he decided to climb the Willis Tower, his teacher, Jeff Kohn, was moved by his determination(决心) and offered      train him. They     more than ten hours practicing climbing stairs and keeping balance with the prosthetics and sticks on the steps every day. “    seems that he never knows how difficult it is.     I was so tired that I asked him to rest for a day,” said Kohn. “But he said he was still full of energy and wanted more     .”
Kohn always walked with McCarthy for the climb. “I  found when climbing the last 10 floors, he went faster,” said Kohn. “He’s the      sportsman I’ve ever trained.”
McCarthy said he was      of himself and that the tower now holds special meaning. “When I’m older, I’ll  point(指着) to the building and      ‘Look at this building I climbed’,”

单项选择题

饮酒后驾驶机动车一次记几分？

A．2分

B．3分

C．6分

D．12分