如图为氢氧燃料电池示意图，按此图的提示，下列叙述不正确的是(_爱下问搜题

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问题选择题

如图为氢氧燃料电池示意图，按此图的提示，下列叙述不正确的是(　　)。

A．a电极是负极

B．b电极的电极反应为：4OH^－－4e^－=2H₂O＋O₂↑

C．氢氧燃料电池是一种具有应用前景的绿色电源

D．氢氧燃料电池是一种不需要将还原剂和氧化剂全部储藏在电池内的新型发电装置

答案

答案：B

a电极上发生反应：H₂－2e^－=2H^＋，是负极；b电极上发生反应：O₂＋2H₂O＋4e^－=4OH^－，是正极。氢氧燃料电池的能量效率较高，而且产物H₂O是一种无污染物质，是一种具有应用前景的绿色电源，其在航天领域已得到应用。氢氧燃料电池通入H₂、O₂就能工作，无需将燃料储藏在电池内部，故正确答案为B。

完形填空

Miracles（奇迹）will happen if you don't give up trying. Even if you have 16 for one hundred times, you may succeed when you try for the 10lst time.
When I was born, my doctor told my mother that there was something wrong with my 17 . They were too soft to be able to walk. Although the news was bad, my mother didn't become 18 . She didn't believe what the doctor said 19 started to look for other ways.
My mother kept looking for other doctors for me, and finally she 20 . The doctor and his team in the hospital did 21 they could to help me. They also asked my parents to teach me to do some 22 to help me walk. One day when my mother came to pick me 23 . I crawled(爬) towards her. She was so surprised and happy that she couldn't believe 24 eyes. Crawling was not walking, but it was a good 25 . Day by day, I could walk by myself.
When I grew up, my mother 26 told me these stories. She said that if I thought of what she said whenever I met 27 , I could do anything successfully. I have been working hard and I have turned out to be a very 28 person. I get best 29 in school and I am a good dancer and swimmer. Thanks to my mother's strong resolution(决心), I live a 30 life now. What the story tells us, as my mother always says, is: Never give up.

C．frustrated(沮丧的)

B．experiments

D．difficulties

选择题

同周期的X、Y、Z三种元素，已知其最高价氧化物对应的水化物的酸性强弱顺序是：

HXO₄＞H₂YO₄＞H₃ZO₄，则下列各判断中正确的是

A．单质的非金属性：X＞Y＞Z

B．原子半径：X＞Y＞Z

C．气态氢化物稳定性：X＜Y＜Z

D．原子序数：X＜Y＜Z