题干

实验室用98%的浓硫酸和蒸馏水配制稀硫酸.

(1)将100克98%的浓硫酸配成19.6%的稀硫酸,需要加____  g蒸馏水进行稀释.

(2)量取和混匀操作中需要的玻璃仪器包括量筒、胶头滴管、玻璃棒和____ 

(3)若量取水时俯视读数,其他操作均正确,则配出的稀硫酸的浓度比19.6%____ 

上一题 下一题 0.0难度 选择题 更新时间:2018-01-08 09:41:29

答案(点此获取答案解析)

400,烧杯,大

同类题5

阅读理解

    When it comes to generation gap (代沟), we usually think of different tastes in music, or pastimes. But now the generation gap is handwriting. After one teacher in Tennessee discovered that she had students who couldn't read what she was writing on the board, she posted it on the Internet saying that handwriting should be taught in schools.

    Others who are against it claim that handwriting has become out of time in our modern world. Typed words have become a main form of communication. Once a practical skill, handwriting is no longer used by most of Americans. It is no longer taught in schools, and some claim that the time that it would take to teach it could be put to better use, for example, by teaching the technical skills.

    But even in today's world there are still plenty of reasons to pick up a pen and write on the paper. In America, signatures (签字) by hand are still often required, for example, signing for a registered letter and buying a house. And original signatures are much more difficult to fake (伪造).

    There is also strong evidence that writing by hand is good for the mind. It makes a different part of the brain active and improves fine moving skills in young children. People are also more likely to remember what they write by hand than what they type, and the process of writing by hand has been shown to stimulate ideas. Not only those, studies have shown that kids who write by hand learn to read and spell earlier than those who don't.

    Yes, we live in a modern world, but we live in a modern world of basic and important values.