化学使生活更美好。下列做法不可行的是 A.用酚酞检验氢氧化钠溶液和碳酸钠溶液 B 发布时间:2017-06-23 20:47 │ 来源:www.tikuol.com 题型:选择题 问题: 化学使生活更美好。下列做法不可行的是A.用酚酞检验氢氧化钠溶液和碳酸钠溶液 B.用食醋除水垢C.用熟石灰可降低土壤酸性D.用生石灰作食品干燥剂
题型:选择题 Questions 17 to 20 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions. Now listen to the passage.Why was the speed limit first reduced to 55 miles-per-hourA.The older people wanted it.B.The voters decided on it.C.It was decided that speeds above that were not safe.D.The US had a fuel crisis. 查看答案
题型:选择题 长途运输鱼苗时,要往盛鱼苗的容器中加入固体过氧化钙(CaO2);固体与水接触时,缓缓放出气体.小军猜想该气体是氧气,供鱼苗呼吸,确保顺利运输.(1)小军应设计怎样的实验来验证该气体是氧气?实验操作:______;观察到的现象:______.(2)小军认为过氧化钙与水反应得到的溶液为氢氧化钙溶液.他往溶液中通入少量二氧化碳,果然出现预期的现象.你认为小军观察到的现象是:______. 查看答案