【简答题】将下列段落翻译成中文 For a neutron - initiated chain- reaction, there must be a critical mass of the element present in a certain space under certain conditions. The conditions for the smallest critical mass re...
【单选题】According to the table of standard reduction potentials at 25 o C, The equilibrium constant for the reaction, Sn(s) + 2 H + → Sn 2+ + H 2 (g) at 25 o C is:(根据下面25 o C时的标准还原电位表,以上反应在25 o C时的平衡常数是:) hal...
【单选题】The standard enthalpy changes of combustion of glucose and ethanol are given as –2820 and 368kJ mol–1 respectively.Glucose, C6H12O6, can be converted into ethanol. H12O6(s) → 2C2H5OH(l) + 2CO2(g) wh...
【简答题】1932年美国化学家鲍林首先提出了电负性的概念。电负性(用X表示)也是元素的一种重要性质,下表给出的是原子序数小于20的16种元素的电负性数值。注意阅读分析材料,据此完成下列要求。 元素 H Li Be B C N O F 电负性 2.1 1.0 1.5 2.0 2.5 3.0 3.5 4.0 元素 Na Mg Al Si P S Cl K 电负性 0.9 1.2 1.5 1.7 2.1 2.3 ...