我国江西赣州蕴藏着丰富的钨矿资源，被称为“世界钨都”．冶炼金_爱下问搜题

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问题选择题

我国江西赣州蕴藏着丰富的钨矿资源，被称为“世界钨都”．冶炼金属钨（W）的重要反应是X+3H₂W+3H₂O．下列说法正确的是（　　）

A．该反应属于化合反应

B．该反应中钨元素的化合价没有变化

C．X的化学式为WO₃

D．该反应中氢元素的化合价均为+1价

答案

由反应的化学方程式X+3H₂

高温

.

W+3H₂O，反应后W和3H₂O中含有1个W原子、6个H原子和3个O原子，而反应前3H₂中只含有6个H原子，则X分子由1个W原子和3个O原子构成，物质X的化学式为WO₃；

A、该反应的化学方程式WO₃+3H₂

高温

.

W+3H₂O，反应为一种单质与一种化合物生成一种单质与一种化合物的置换反应，而不属于化合反应，故选项A不正确；

B、根据化合物中各元素化合价代数和为0，可知反应前WO₃中W元素化合价为+6价，而反应后单质W中W元素化合价为0价，反应前后W元素的化合价由+6价变为0价，故选项B不正确；

C、由反应的化学方程式X+3H₂

高温

.

W+3H₂O，物质X的化学式为WO₃；因此选项C是正确的；

D、反应前H₂中H元素化合价为0价，反应后H₂O中H元素的化合价为+1价，反应中氢元素的化合价由0价变为+1价，故选项D不正确；

故选C．

问答题简答题

简述学习困难学生。

完形填空

One dark stormy night an elderly couple hurried into a hotel and asked whether they could be 36 for the night." I’m very sorry,” the clerk on night shift said politely, "we are all 37 tonight． 38 ,you
could stay in my room if you don't mind．I’m 39 , so I'll be here．“ The young man gave the sincere advice．
The elderly couple accepted his 40 with gratitude．They apologized for the 41 they had caused him．The next day, the rain stopped and it 42 ．When the old gentleman went to pay his bill, the same clerk said．" The room you and your wife stayed in is not a proper 43 room in this hotel, so you don't need to pay．”
The old gentleman nodded in 44 : “You are an employee that every boss in the hotel business would dream of．Perhaps someday I’ll build a hotel for you．”The clerk was__45 but, deciding that the
guest must have been 46 , he gave the remark 47 thought．
Two years later, the young man received a registered letter from the old gentleman, in which he 48 the experience of that dark stormy night．The letter also 49 a formal invitation, asking that young man to pay a visit．
At a street comer in Manhattan, the young man met his 50 guest．The old gentleman, pointing
to a magnificent new building__51 over the crossroads, said, "Look, that is the hotel I 52 to build for you．I hope you will 53 it for me．Remember what I said then? Well, I was 54 about it．”
The young man stammered, "But…will there be any 55 ,sir? Why do you choose me? And who are you?"
“My name is William Aster．”This building was none other than the Waldorf Astoria Hotel, a symbol of supreme status and honor in New York．

A．instruction

B．consideration

C．inconvenience

D．interruption

A．cleared away

A．appreciation