题目

用长度放大600倍的显微镜观察布朗运动，估计放大后的小颗粒(碳)体积为0.1×10-9 m3，碳的密度是2.25×103 kg/m3,摩尔质量是1.2×10-2 kg/mol,阿伏加德罗常数为6.02×1023 mol-1,则该小碳粒含分子数约为__________个(取一位有效数字)，所以布朗运动不是分子运动. 答案：5×1010 解析:实际碳颗粒的体积为      V= m3     碳颗粒的质量为     m= kg     碳颗粒的物质的量为     n= mol     碳颗粒的个数为     N=×6.02×1023个≈5×1010个. 第二节 短文改错 （共10小题；每小题1．5分，满分15分）          此题要求改正所给短文中的错误。对标有题号的每一行做出判断：          如无错误，该行右边横线上画一个勾（√）；          如有错误（每行只有一个错误），则按下列情况改正：          此行多一个词：把多余的词用斜线（＼）划掉，在该行右边横线上写出该词，并也用斜线划掉。          此行缺一个词：在缺词处加一个漏字符号（∧），在该行右边横线上写出该加的词。          此行错一个词：在错的词下划一横线，在该行右边横线上写出改正后的词。          注意：原行没有错的不要改。 Mother’s Day was around the corner. My good friend                                 76. __________ Alice, Jenny and I get together, discussing what we should do to         77. __________ our respect for. Alice was planning to buy some flowers with                  78. __________ his pocket money in honor of her mother. Jenny was going to buy         79. __________ vegetables to cook delicious dinner for her family on that day, because80. __________ she wanted to experience how many her mother does for her family   81. __________ every day. As for me, I’d like to make a greeting card, said                      82. __________ “Happy Mother’s Day”, in which I would also tell my mother                  83. __________ to pay attention to health or promise her to study harder.                       84. __________ We are looking forward to Mother’s Day.       85. __________