题干

用NA表示阿伏德罗常数,下列叙述正确的(  )

A:标准状况下,22.4LH2O含有的分子数为1 NA

B:常温常压下,1.06g Na2CO3含有的Na+离子数为0.02 N

C:通常状况下,1 NA个CO2分子占有的体积为22.4L

D:标准状况下,22.4L CO2和SO2混合气中氧原子数为0.2NA

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答案(点此获取答案解析)

B

同类题3

阅读下面材料,在横线上填入一个恰当的词语,或填入括号中所给单词的正确形式。

    Students at Shanming Middle School in Jiangsu often take part in activities____ (hold) by nearby communities. Does it sound fun? Well, students have mixed feelings. They enjoy the time outside school. But they don't find the activities  ____ (interest).

Why not design____  (they) own activities? Some students got this idea and soon students joined the project.

     They first thought about activities ideas and listed them in an “activity menu”. They included: visiting science museums and companies; watching movies and basketball competitions.

    “The menu looked great, ____  we soon found problems,” said Wang Ziming, one of the____   (designer).

      First they needed a place to hold the activities. The students decided to talk to the local government to let them use the district stadium.

 “We first presented the benefits of these community activities to them,” said Wang. “ Then we promised we'd use the stadium ____  (careful ) and clean it afterwards”.

     The local government agreed that they could use the stadium and some sports equipment once____  month.

     The students also designed a virtual (虚拟的) bank to encourage volunteering.

     Students____   volunteered as librarians or cleaners would be rewarded with “gold coins”. A certain amount of coins gave you free entry to entertainment events such as____ (watch) a movie.

     Now, this special activity menu ____ (become) popular in Wuxi communities. The students are happy with this.