This indicates... A. A physical change B. A chemical change C. No change D. A wrong E. xperiment 相关知识点: 试题来源: 解析 B。物质气味改变通常是化学变化。选项 A 物理变化一般不涉及气味明显变化;选项 C 有变化;选项 D 不是错误实验。反馈 收藏 ...
A substance that takes part in a chemical reaction is called a ___. A. reagent B. product C. catalyst D. solvent 相关知识点: 试题来源: 解析 A。参与化学反应的物质叫试剂,“reagent”是试剂,“product”是产物,“catalyst”是催化剂,“solvent”是溶剂。反馈 收藏...
In a precipitation reaction, a solid substance forms and is called a ___. A. solute B. solvent C. precipitate D. suspension 相关知识点: 试题来源: 解析 C。在沉淀反应中,形成的固体物质叫做沉淀物。solute 是溶质;solvent 是溶剂;precipitate 是沉淀物;suspension 是悬浊液。所以选沉淀物。反馈...
A substance that speeds up a chemical reaction without being consumed is called___. A. reactant B. product C. catalyst D. solute 相关知识点: 试题来源: 解析 C。解析:加快化学反应但自身不被消耗的物质叫催化剂。选项 A 反应物会被消耗;选项 B 产物是反应生成的;选项 D 溶质不是起这个作用。反...
In a science experiment, it was found that when substance A reacts with substance B, a new compound is formed. But if substance C is added, the reaction stops. Now, if substance A and B are mixed and substance C is also present, what will happen? A. A new compound will be formed...
In a chemical reaction, the amount of substance G is twice that of substance H. If there are 8 grams of substance H, how many grams of substance G are there? A. 4 grams B. 8 grams C. 16 grams D. 32 grams 相关知识点:
What is the name of the substance that changes the rate of a chemical reaction without being consumed? A. Reactant B. Product C. Catalyst D. Solute 相关知识点: 试题来源: 解析 C。这里考查“catalyst”(催化剂)的概念,它能改变反应速率但自身不被消耗。选项 A“reactant”是反应物;选项 B“...
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。选项 A 克是质量单位;选项 B 升是体积单位;选项 C 微粒,1 摩尔物质含有阿伏伽德罗常数个微粒,所以与摩尔有对应关系;选项 D 千克是质量单位。反馈 收藏
In a certain chemical reaction, the amount of a substance increases by a factor of 4 every 5 minutes. If the initial amount was 10 grams, how much will there be after 15 minutes? A. 160 B. 640 C. 40 D. 1600 相关知识点:
The substance that speeds up a chemical reaction without being consumed itself is a ___. A. product B. reactant C. catalyst D. solvent 相关知识点: 试题来源: 解析 C。catalyst 是催化剂,能加快化学反应速度但自身不被消耗;product 是产物;reactant 是反应物;solvent 是溶剂。所以选催化剂。反馈...