题干

某气体的摩尔质量为M,摩尔体积为V,密度为ρ,每个分子的质量和体积分别为m和Vo,则阿伏加德罗常数NA可表示为(   )

A:NA= Mm

B:NA= ρVm

C:NA= VV0

D:NA= MρV0

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A,B

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    For the past 15years, factory owner Kamal Parmar has been running an after-school program for slum kids in Ahmedabad, India, helping them with basic skills like reading and writing and even preparing for their school tests.

    Parmar's story began one afternoon 15 years ago. He stopped a few kids returning home from the local school and took their exam paper and asked them a few questions. Shockingly, he made a shocking discovery--the students, even the older ones, knew nothing about reading except the alphabet. And that left him thinking that something should be done for these children.

    So he invited the kids to visit his workshop every evening, where he set up a temporary classroom with metal desks. The shabby school started off with 10 students. Today, the Footpath School has a total of 155 students and many of the kids that Parmar has taught in the past 15yearshav e gone to attend college and build successful careers.

    Despite having studied only till the seventh grade, he has been able to teach the kids by inventing creative techniques. He asks them to read first and then to form questions on their own and read them out. In this way, many kids learn all seven subjects in six months.

    Parmar's family are very supportive of his project and are proud to see how much of an impact he has had on the kids. His students love him. Ten of his ex-students are currently serving as teachers at the school and he doesn't have to employ any teachers.

    For those who are inspired by his story, but can't actually volunteer at school, Parmar has a simple piece of ads ice: “Try to educate just one child a year, and see the difference it makes to the society.”