20. 一質量均勻的繩子，長度為L，兩端分別受力F1、F2之作用，則距F1作用之一端x距離處，繩子之張力為何？

6. Given that the enthalpy required to convert CHCl3(g) to gaseous C, H, and Cl atoms is 1397 kJ/mol and that the dissociation enthalpy of a C-H bond is 413 kJ/mol, what is the bond dissociation enthalpy of a C-Cl bond？ (A)328 kJ/mol　(B)603 kJ/mol　(C)984 kJ/mol　(D)1397 kJ/mol