Which of the following is NOT a sign of a chemical reaction? A. Color change B. Temperature rise C. Shape change D. Gas production 相关知识点: 试题来源: 解析 C。本题考查化学反应的标志。颜色变化、温度上升、产生气体都是化学反应的常见标志,形状改变通常不是化学反应的标志。
A. color B. size C. shape D. weight 相关知识点: 试题来源: 解析 A。解析:化学反应经常会有颜色变化。选项 B 尺寸变化一般不是化学反应的主要特征;选项 C 形状变化也不是化学反应常见的特征;选项 D 重量变化不一定在化学反应中普遍发生。反馈 收藏 ...
Chemical reactions often involve changes in substances. Which of the following is an indication of a chemical reaction? A. Change in color B. Change in shape C. Change in size D. Change in position 相关知识点: 试题来源: 解析 A。颜色变化通常是化学反应的标志之一。形状、大小和位置的变化一般...
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Which term is defined as new substances formed from chemical reactions? What is a chemical property? What reactions create stereochemistry? What does a color change indicate the formation of in chemistry? What is the chemical reaction of oxygen with other substances?
Since you can't look at chemicals at a molecular level with the naked eye, it's helpful to know signs that indicate a reaction has occurred. A chemical reaction is often accompanied by a temperature change, bubbles, color change, and/or precipitate formation. ...
A语篇类型:说明文 主题语境:人与自我 词数:283 难度:★★★(2022· 江苏省淮海中学高二开学考试)How doeskeepingthingstidychangepeoplepsychologically? Yougaingreaterconfidenceinyourself.Also,youbecomemoreoptimisticandcalmerinthemindthanbefore.Thereareseveralreasonsforthesechanges:yourself-imageimprovesasyoustartliving...
”The set of speech sounds we use has not necessarily remained stable since the appearance of human beings, but rather the huge variety of speech sounds that we find today is the product of a complex interplay of things like biological change and cultural evolution,“ said Steven Moran, a ...
The titrant is added until the chemical reaction is complete and the end of the titration reaction is easily detected by appropriate techniques (e.g. potentiometry or color change of a suitable indicator). The reaction involved in a titration must therefore be fast, complete, unambiguous and obse...