论文部分内容阅读
一、选择题(本大题共12小题,每小题5分,共60分.在每小题给出的4个选项中,只有1项是符合题目要求的.)1.已知甲烷的分子结构是:中心为一个碳原子,外围有4个氢原子(这4个氢原子构成一个正四面体的四个顶点).设中心碳原子到外围4个氢原子连成的4条线段两两组成的角为θ,则cosθ的值是( ).
First, the multiple-choice questions (the title of a total of 12 small questions, each question 5 points, a total of 60 points. Among the four options given in each question, only one is in line with the requirements of the title.) 1. known methane The molecular structure is: the center is a carbon atom, and the periphery has 4 hydrogen atoms (the 4 hydrogen atoms form the four vertices of a regular tetrahedron). 4 line segments are formed by connecting the central carbon atom to the outer 4 hydrogen atoms. The angle of the pair of two is θ, then the value of cosθ is ().