问题 填空题

元素R有两种氯化物RClm和RCln,其相对分子质量之差为71,Cl的质量分数在RClm中为85%,在RClm中为77%,则:

(1)m-n=______________,m=______________,R的相对分子质量=______________;

(2)通常R有两种同素异形体,其名称是__________________和________________。

答案

(1)2  5  31 (2)白磷 红磷

依题意易得:m-n=2。

由RClm和RCln及m-n=2可联想到PCl5和PCl3,代入验证:

PCl5中:w(Cl)=×100%≈85%

PCl3中:w(Cl)= ×100%≈77%

符合题意,则RClm和RCln分别为PCl5和PCl3

完形填空

第一节完形填空(共15小题;每小题2分.满分30分)

阅读下面短文,掌握其大意.然后从1—15各题所给的A、B、C和D项中,选出最佳选项,并在答题卡上将该项涂黑。

Friendship has great power, and it can inspire the people in trouble as well as in easy circumstances.

Recently, one of my best friends, whom I've   1        just about everything with since the first day of kindergarten, spent the weekend with me. Since I   2       to a new town several years ago, we've both always looked forward to the few  times a year when we can see each other.

Over the weekend, we   3      hours and hours, staying up late into the night, talking about the people she was hanging around with. She started telling me stories about her new boyfriend, about how he  4      with drugs and was into other self-destructive[自毁]   5    . I was blown away! She told me how she had been   6       to her parents about where she was going and even sneaking out to see this guy because they didn't want her around him. No matter how hard I tried to tell her that she deserved better, she didn't believe me. Her self-respect seemed to have disappeared.

I tried to convince her that she was ruining her future and heading for big   7     . I felt like I was getting nowhere. I just couldn't believe that she really thought it was acceptable to hang with a bunch of losers, especially her boyfriend.

By the time she left, I was really worried about her and   8         by the experience. It had been so  9       , I had come close to telling her several times during the weekend that maybe we had just grown too far apart to continue our friendship, but I didn't. I put the         10         of friendship to the  11        test. We'd been friends for far too long. I had to hope that she  12       me enough to know that I was trying to save her from hurting herself. I wanted to believe that our friendship could conquer anything.

A few days later, she called to say that she had thought long and hard about our   13      , and then she told me that she had   14      with her boyfriend. I just listened on the other end of the phone with tears of joy running down my face. It was one of the   15      rewarding moments in my life. Never had I been so proud of a friend.

1. A. divided               B. shared                      C. experienced                     D. enjoyed

2. A. got                            B. traveled                    C. moved                            D. arrived

3. A. took                   B. spared                      C. offered                     D. spent

4. A. supplied              B. experimented            C. tried                        D. provided

5. A. action                 B. movements               C. behavior                   D. activities

6. A. explaining           B. speaking                   C. calling                            D. lying

7. A. trouble               B. worry                      C. difficulty                  D. task

8. A. burned down              B. turned down             C. turned out                D. worn out

9. A. discouraging              B. encouraging              C. exciting                    D. inspiring

10. A. strength                     B. force                        C. power                      D. energy

11. A. last                     B. final                        C. late                          D. recent

12. A. treated                B. regarded                   C. honored                   D. valued

13. A. information         B. dialogue                   C. conversation             D. communication

14. A. broken out          B. broken up                 C. broken away             D. broken off

15. A. luckily                B. correctly                  C. naturally                  D. truly

填空题