科学家曾通过测定古生物遗骸的碳-14含量来推测古城年代．碳14原子的核电荷数为6，相对原子质量为14．下列关于碳14原子的说法中错误的是
A．中子数为6
B．质子数为6
C．电子数为6
D．质子数与中子数之和为14
答案：A
题目分析：在原子的结构中，核电荷数=质子数=核外电子数，相对原子质量=质子数+中子数，根据题意可求得核电荷数=质子数=核外电子数=6，中子数=14-6=8，故B、C、D正确，A错误，应选A。
点评：解答此类试题，要求学生记住在原子结构中，各个个数之间的关系。
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| Jennifer was sitting on the beach. After all she had been through, it was just what she needed. It’s getting __1__,“ she thought. “I should go home.” She wanted to know how her __2__ would react*, when she __3__ home after the three days she was missing. It was really dark when she finally reached her front door. It seemed different to her. __4__ had taken care of the outside garden for __5__ days. She was surprised as her father usually worked hard to keep everything __6__ and tidy*. She couldn’t understand what was going on. She entered the __7__. First, she went into the kitchen __8__ she saw a note written by her father. __9__said, “Dear Ellen, here is some coffee. I am out searching*.” Ellen was her mother, but where was she? She went to her parents’ room. She found her there. Her __10__ was lying on the bed, fast sleep. Her face looked so __11__, as if she hadn’t slept for days. Jennifer wanted to wake her up __12__ she looked too tired. So Jennifer just fell asleep beside her. When Jennifer __13__, something was different: she wasn’t in her mother’s room anymore and she wasn’t wearing the old clothes she ran away __14__. She was on her own bed. It felt so good being back home. Suddenly she heard a voice ask, “Are you feeling better now, dear? You know you __15__ us all very, very scared.” | |||
| ( )1. A. early ( )2.A. father ( )3.A. got ( )4.A. Everybody ( )5.A. many ( )6.A. clean ( )7.A. school ( )8.A. what ( )9.A. They ( )10.A. mother ( )11. A. happy ( )12.A. and ( )13.A. got up ( )14.A. out ( )15.A. had | B. late B. mother B. left B. Somebody B. lots of B. dirty B. room B. when B. It B. father B. tired B. so B. woke up B. on B. let | C. warm C. parents C. wanted C. Anybody C. a few C. quiet C. house C. who C. He C. friend C. scared C. but C. put up C. of C. made | D. angry D. teachers D. missed D. Nobody D. much D. busy D. library D. where D. She D. sister D. relaxed D. although D. clean up D. in D. gave |