问题 选择题

用单分子油膜测分子的直径时,对其所用实验方法的正确认识是

A.用量筒测得油酸酒精溶液的体积V,计算油酸分子直径时要用到d="V/s"

B.用透明方格纸,是为了便于估算一滴油酸溶液形成的油膜面积

C.在水面上撒些痱子粉,是为了让油膜尽量散开并呈现圆形

D.在水面上撒些痱子粉,是为了围住油膜形成规则形状

答案

答案:B

分析:将配制好的油酸酒精溶液,通过量筒测出此溶液的体积.然后将此溶液滴在有痱子粉的浅盘里的水面上,等待形状稳定后,将玻璃板放在浅盘上,用彩笔描绘出油酸膜的形状,将画有油酸薄膜轮廓的玻璃板放在坐标纸上,按不足半个舍去,多于半个的算一个,统计出油酸薄膜的面积.则用此溶液的体积除以其的面积,恰好就是油酸分子的直径.

解答:解:A:用量筒测得油酸酒精溶液的体积V,计算油酸分子直径时要用到d= V/s.是本实验的操作步骤.故A选项不正确

B:用透明方格纸就可估算出油膜的面积,这是实验方法的体现.故B选项是正确的

C:在水面上撒些痱子粉,是为了让油膜尽量散开并呈现圆形.也是实验操作步骤,故C选项不正确.

D:撒些痱子粉,不是为了围住油膜形成规则形状,而是让油酸形成单分子油膜,且一个靠着一个.故D不正确.

故选为B.

点评:本题是以油酸分子呈球型分布在水面上,且一个挨一个,从而可以由体积与面积相除求出油膜的厚度.

完形填空
My husband and l were talking about possible colours because it was time for painting the kitchen again. The children, sat nearby and suddenly shouted, "Not the measuring(测量)stick!”
The measuring stick isn't a real stick but the kitchen side of the door between our kitchen and the dining room. Along the edge we have   each child's growth by making a mark showing his or her    on every birthday. Over the ten years so many    pens, pencils and markers were used that the door came to be   like a painting.
Names and dates   different hand-writing, and I can   by the script(手迹)who measured whom. An eight-year-old brother measured his three-year-old sister, a grandchild measured her grandmother, my husband measured me. At parties, when this door swings, friends stop to     the names and dates. When we ask if they would like to leave their marks, they usually had a smile.
Many of these listed on the door are still    While some have stopped. Some is still with us only in memory. When my mother came to see our eldest daughter graduating from university, we measured her, too. It was her last visit to our home.
We haven't decided on the new kitchen colour plan yet, but one thing is   :Whether we paint the trim curry gold, Chowning's Tavern red or Federal blue, the back of the kitchen door will be always     with lots of names and dates in different colors.
小题1:
A.celebratedB.explainC.encouragedD.congratulated
小题2:
A.progressB.weightC.heightD.size
小题3:
A.newB.colouredC.longD.short
小题4:
A.simplyB.clearlyC.unusuallyD.unclearly
小题5:
A.makeB.showC.giveD.keep
小题6:
A.tellB.understandC.remindD.think
小题7:
A.findB.noticeC.readD.write
小题8:
A.changingB.addingC.puttingD.growing
小题9:
A.curiousB.certainC.readyD.common
小题10:
A.whiteB.redC.goldD.blue
单项选择题 B1型题