【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...
【简答题】Dinitrogen pentaoxide, N 2 O 5 , is the anhydride of nitric acid. It is not very stable, and in the gas phase or in solution with a nonaqueous solvent it decomposes by a first-order reaction into N 2 ...
【简答题】It is difficult to prepare many compounds directly from the elements,so values for these compounds cannot be measured directIy. For many organic compounds,it is easier to measure the standard enthalpy...