题目

用NA表示阿伏加德罗常数的值，下列说法中正确的是 A．5.6g铁与足量盐酸反应转移的电子数为0.3NA B．常温下，2.7g铝与足量的盐酸反应，失去的电子数为0.3NA C．标准状况下，22.4L氦气与22.4L氟气所含原子数均为2NA D．18g NH所含电子数为11NA 答案：【答案】B 【解析】A．5.6g铁的物质的量为0.1mol，与足量盐酸反应生成0.1mol Fe2+，所以转移的电子数为0.2NA，A不正确；B．2.7g铝的物质的量为0.1mol，与足量的盐酸反应失去的电子数为0.3NA，B正确；C．氦气是单原子分子，所以在标准状况下，22.4L氦气所含原子数为NA，C不正确；D．每个NH中有10个电子，18g NH的 第二节：完形填空（共20小题；每小题1.5分，满分30分） 阅读下面短文，掌握其大意，然后从36—55各题所给的四个选项（A、B、C和D）中，选出最佳选项。 Our area was just a few miles from the largest wildfire in Colorado’s history. We were on “evacuation alert (疏散警报)”. If we got the  36  to evacuate, we would have to leave immediately. We  37 suitcases with some clothes and set them by the door. We didn’t 38  these things were valuable, but time was. We moved the computers, with which I wrote for newspapers and made a  39 . We took family pictures off the  40  and packed them in boxes. Then we took a hard look at all that  41 . There was a lamp that belonged to my great grandmother. It was a  42  to my family. And there was the piano my wife Bev  43  to play when she was a little girl. Not of great  44  in itself, but another family connection. The thought of  45  something passed down from our families saddened me deeply, 46  I’d never been much attached to things. It’s about what they  47  －family and love. They each had a(n)  48  to tell, and some of them spoke in the  49  of our parents and grandparents. The fire  50  reached our home. We were lucky. And though I felt grateful that all was 51 , I also realized just how fortunate I had been  52  . I saw just how rich my life had been. Someone  53  said, “There are people so poor that the only thing they have is money.” And now I  54 . I was indeed rich. I was rich in family, rich in memories, rich in everything that really  55 . I wonder if there is any other kind of wealth worth seeking. 36．A．answer    B．call       C．chance          D．task 37．A．sold      B．bought    C．searched         D．packed  38．A．worry      B．care        C．think       D．doubt 39．A．mark      B．living      C．sign        D．plan 40．A．walls      B．ceilings  C．windows        D．albums 41．A．left         B．burnt      C．remained        D．unmoved 42．A．present    B．connection     C．symbol          D．treasure 43．A．learned          B．agreed   C．forgot     D．refused 44．A．quality    B．taste        C．value      D．sense 45．A．knocking out   B．picking out     C．giving away    D．leaving behind  46．A．but         B．unless     C．even though          D．or 47．A．contained      B．included   C．represented   D．gathered 48．A．idea      B．lie          C．right       D．story 49．A．sounds          B．voices   C．speeds   D．feelings 50．A．never     B．once       C．seldom          D．finally 51．A．returned        B．spared     C．stopped         D．found 52．A．in another way       B．in return         C．at last      D．at most 53．A．curiously        B．accidentally          C．wisely     D．coldly 54．A．promised       B．knew      C．announced     D．thanked  55．A．affects    B．desires    C．helps       D．counts