If the starting and ending substances are the same, a change may have occurred, but not a chemical reaction. A reaction involves a rearrangement of molecules or ions into a different structure. Contrast this with aphysical change, where the appearance is altered, but the molecular structure is ...
百度试题 结果1 题目8. On what basis is a chemical reaction balanced? 相关知识点: 试题来源: 解析 Chemical equation is balanced on the basis of law of conservation of mass. 反馈 收藏
The alternative equation is also balanced and does not call for matter to be created or destroyed. Let's express the reaction in words in case someone is reading the chemical notation incorrectly: On the left side we have one atom of copper metal at oxidation state zero and two molecules of...
What is the term used to describe a chemical reaction that produces energy in the form of heat or light? A. Endothermic reaction B. Exothermic reaction C. Isothermal reaction D. Photochemical reaction 相关知识点: 试题来源: 解析 B 反馈 收藏 ...
In order for the chemical reaction to take place smoothly, what condition is needed? A. presence of a catalyst B. absence of oxygen C. high humidity D. low light intensity 相关知识点: 试题来源: 解析 A。考查化学反应条件。选项 A 有催化剂存在可以使化学反应更顺利地进行。选项 B 没有氧气...
百度试题 结果1 题目What is the difference between a chemical reaction and a physical change?相关知识点: 试题来源: 解析 Chemical changes produce new substances,not a physical change 反馈 收藏
In a chemical reaction, if the pressure is increased, what will happen to the reaction rate? A. Decrease B. Remain unchanged C. Increase D. Depend on the reaction 相关知识点: 试题来源: 解析 C。解析:对于有气体参与的反应,增加压力通常会增加反应速率,因为压力增加会使气体分子间距离减小,碰撞...
In a chemical reaction, iron reacts with oxygen to form rust. What is the English name for iron? A. Copper B. Aluminum C. Iron D. Silver 相关知识点: 试题来源: 解析 C。本题考查铁的英文名称。选项 A 是铜,选项 B 是铝,选项 D 是银。只有选项 C 是铁。
Chemical reaction A is represented by the equation: 2H₂ + O₂ = 2H₂O. What does this e
A. Rough and hard B. Smooth and slippery C. Fluffy and light D. Sticky and heavy 相关知识点: 试题来源: 解析 C。化学实验中的沉淀通常是蓬松且轻的,比如碳酸钙沉淀等。选项 A 粗糙坚硬的沉淀较少。选项 B 光滑滑溜的不是沉淀的常见特征。选项 D 粘滞且重的一般不是沉淀的特点。反馈 收藏 ...