用铅蓄电池电解甲、乙电解池中的溶液。电解一段时间后向c极和d_爱下问搜题

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问题选择题

用铅蓄电池电解甲、乙电解池中的溶液。电解一段时间后向c极和d极附近分别滴加酚酞试剂，c极附近溶液变红，下列说法正确的是（）

A．d极为阴极

B．若利用甲池精炼铜，b极应为粗铜

C．放电时铅蓄电池负极的电极反应式为：

PbO₂(s) ＋ 4 H^＋(aq)＋SO₄²^－(aq)＋4e^－ = PbSO₄ (s) ＋2H₂O (l）

D．若四个电极材料均为石墨，当析出6．4 g Cu时，两池中 * * 生气体3．36 L(标准状况下)

答案

答案：B

题目分析：在这两个电解池中由于是串联电路，所以电子转移的物质的量相等，电解一段时间后滴加酚酞试剂，c极附近溶液变红，说明在该电极溶液显碱性，则是H+在c电极放电，所以c是阴极，d是阳极。则a是阴极。B是阳极。故选项A错误；若利用甲池精炼铜，b极由于是阳极，所以应为粗铜，选项B正确；C．放电时铅蓄电池负极的电极反应式为：Pb (s) -2e^-＋SO₄²^－(aq) = PbSO₄ (s),选项C错误。D．若四个电极材料均为石墨，当析出6．4 g Cu时，则电子转移(6．4g÷64g/mol)×2=0．2mol。在甲池b电极产生Cl₂0．1mol，在乙池实质就是电解水，2H₂O通电2H₂↑+ O₂↑,若转移电子0．2mol，则乙池产生气体的物质的量是0．15mol，所以两池中 * * 生气体的物质的量是0．25mol ，在标准状况下，其体积是0．25mol ×22．4L/mol=5．6 L,所以选项D错误。

判断题

微束等离子弧焊有两种引燃非转移弧的方法。( )

完形填空

I will never forget the year I was about twelve years old. My mother told us that we would not be _36_ Christmas gifts because there was not enough money. I felt sad and thought, “What would I say when the other kids asked what I’d 37 ?” Just when I started to 38 that there would not be a Christmas that year, three women 39 at our house with gifts for all of us. For me they brought a doll. I felt such a sense of 40 that I would no longer have to be embarrassed when I returned to school. I wasn’t 41 . Somebody had thought 42 of me to bring me a gift.
Years later, when I stood in the kitchen of my new house, thinking how I wanted to make my 43 Christmas there special and memorable, I 44 remembered the women’s visit. I decided that I wanted to create that same feeling of 45 for as many children as I could possibly reach.
So I 46 a plan and gathered forty people from my company to help. We gathered about 125 orphans (孤儿) at the Christmas party. For every child, we wrapped colorful packages filled with toys, clothes, and school supplies, 47 with a child’s name. We wanted all of them to know they were 48 . Before I called out their names and handed them their gifts, I 49 them that they couldn’t open their presents 50 every child had come forward. Finally the 51 they had been waiting for came as I called out, “One, two, three. Open your presents!” As the children opened their packages, their faces beamed and their bright smiles 52 up the room. The 53 in the room was obvious, and 54 wasn’t just about toys. It was a feeling –the feeling I knew 55 that Christmas so long ago when the women came to visit. I wasn’t forgotten. Somebody thought of me. I matter.

B．settled down

C．achievement

D．occasionally

B．independence

A．kept up with

B．caught up with

C．came up with

D．put up with