已知硫酸亚铁溶液中加入过氧化钠时发生反应:4Fe2++4Na2O2+6H2O==

题型:选择题

问题:

已知硫酸亚铁溶液中加入过氧化钠时发生反应:4Fe2+4Na2O2+6H2O===4Fe(OH)3↓+O2↑+8Na,则下列说法正确的是

A.该反应中Fe2是还原剂,O2是还原产物

B.4 mol Na2O2在反应中共得到8NA个电子

C.Fe(OH)3是氧化产物,每生成1 mol O2反应过程中共转移6 mol电子

D.反应过程中可以看到白色沉淀转化为灰绿色再转化为红褐色沉淀

考点:氧化还原反应与基本反应类型的关系氧化还原反应的本质和特征氧化还原反应的配平氧化还原反应的表示方法
题型:选择题

恐则()

A.气消

B.气上

C.气泄

D.气耗

E.气下

题型:选择题

阅读下面短文,掌握其大意,然后从21—40各题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题纸上将该选项标号涂黑。

During the war,my husband was stationed at an army camp in a desert in California.I went to live there in order to be 21  him. I hated the place .I had never  22  been so unhappy . My husband was ordered out on a long-term duty,and I was left in a tiny shack(棚屋) alone. The heat was  23  -almost 125 0F even in the shade of a cactus(仙人掌)。 24  a soul to talk to . The wind blew non-stop ,and all the food I ate ,and the evry air I breathed,were  25   with sand , sand , sand !

I was so sorry for myself that I wrote to my parents. I told them I was  26   and coming back home.I said I couldn’t stand it one minute longer. I  27  be in prison! My father answered my  28  with just two lines-two lines that will always sing in my  29  - two lines that completely changed my life :

Two men looked out from prison bars

One saw the mud ,the other saw the stars

I read those two lines  30   I was ashamed of myself. I made up my mind I would find out what was good in my present  31  ; I would look for the stars

I made friends with the natives,and their  32  amazed me. They gave me presents of their favorite artworks which they had  33  to sell to toueists . I studied the delightful forms of the cactus .I watched for the desert sunsets,and  34  for seashells that had been left there millions of years ago when the desert had been an ocean  35 

What brought about this  36   change in me ? The desert hadn’t changed , 37   I had .I had changed my  38   And by doing so ,I changed an unhappy experience into the most amazing  39  of my life . I was excited by this new world that I had dicovered I had looked out of my self-creatded prison and  40   the stars

32()

A.movement

B.reaction

C.guidance

D.purpose

题型:选择题

在检修工作的安全技术措施中,挂接地线是检修前重要的安全措施之一。在挂接地线时,先接导体端,后接接地端;拆除顺序与此相反。()

题型:选择题

阴阳两虚

题型:选择题

某机电安装工程公司承接了某机厂的热力锅炉及管道系统的安装工程,工程范围为2套锅炉设备以及连接管道,管道终端需要与原有管道连接。在施工过程中,发生如下事件:(1)施工现场与原有厂区相接,周边行人较多,为确保施工安全,项目部拉设了临时围挡。(2)为保证材料的正确使用和严防丢失,项目部进行了材料管理。(3)管工李某施工现场水平仪丢失,导致他的焊接工作不能继续进行。(4)在蒸汽管道系统施工中,有一条管道与汽包连接时差一小段管道,进行安装的车工在施工现场找到一段直径、壁厚相同的钢管进行了焊接,结果在系统进行压力试验时该部位出现了裂纹,经取样化验结果材质不符。(5)某关键工作因施工质量不合格,返修延误了工期3天。

在工程项目中如何进行施工机具的管理?

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