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。
Which of the following is a chemical reaction? A. Melting ice B. Breaking a glass C. Rusting of iron D. Folding a piece of paper 相关知识点: 试题来源: 解析 C。本题主要考查化学变化的定义。A 选项冰融化是物理变化,物质的状态改变但没有新物质生成。B 选项打破玻璃也是物理变化,只是物质的...
Which of the following is a chemical reaction? A. Melting ice B. Breaking a glass C. Rusting of iron D. Folding a paper 相关知识点: 试题来源: 解析 C。本题考查化学反应的定义。A 选项冰融化是物理变化,物质的状态发生改变但没有新物质生成。B 选项打破玻璃也是物理变化,只是物质的形状发生改变...
A. Decreasing temperature. B. Increasing temperature. C. Increasing the concentration of reactants. D. Using a catalyst. 相关知识点: 试题来源: 解析 A。解析:文章中提到增加温度、增加反应物浓度和使用催化剂都能加快化学反应速率,而降低温度不会加快反应速率。反馈...
百度试题 结果1 题目Of the following factors, which cannot affect the rate of a chemical reaction?相关知识点: 试题来源: 解析 A 反馈 收藏
There is a chemical reaction in which a solid turns into a gas. This is an example of a(n) ___. A. physical change B. chemical change C. mixture D. solution 相关知识点: 试题来源: 解析 B。本题考查物质性质变化的类型。化学变化是指有新物质生成的变化,固体变成气体是有新物质生成的变化...
B. A change in volume. C. A change in mass. D. A change in position. 相关知识点: 试题来源: 解析 A。解析:温度变化是化学反应的一个标志。选项 B 体积变化不一定是化学反应引起的;选项 C 质量变化在一般化学反应中不太明显;选项 D 位置变化与化学反应无关。反馈 收藏 ...
1.6Which ONE of the following statements about a chemical reaction is CORRECT?The actual yield of a chemical reaction is usually ...C A equal to the percentage yield. B greater than the percentage yield. C less than the theoretical yield. D greater than the theoretical yield. 相关知识点:...
In a chemical reaction, the amount of substance can be expressed in moles. Which of the following units is equivalent to a mole? A. grams B. liters C. particles D. kilograms 相关知识点: 试题来源: 解析 C。本题主要考查摩尔的概念。摩尔是物质的量的单位,1 摩尔物质含有阿伏伽德罗常数个微粒...
The present invention relates to process wherein (+)-2-carene epoxide is coupled with a compound X-Y that contains nucleophilic and electrophilic moieties, to produce a compound of formula (5). The reaction mixture consists essentially of a source of (+)-2-carene epoxide, compound X-Y, opt...