题干

已知锌及其化合物的性质与铝及其化合物相似。如图,横坐标为溶液的pH,纵坐标为Zn2离子或[Zn(OH)4]2离子的物质的量浓度(假设Zn2离子浓度为105mol·L1时,Zn2离子已沉淀完全)。下列说法不正确的是

A:往ZnCl2溶液中加入足量的氢氧化钠溶液,反应的离子方程式可表示为:
Zn2+4OH=Zn(OH)42

B:从图中数据计算可得Zn(OH)2的溶度积Ksp=1017

C:某废液中含Zn2离子,沉淀Zn2离子可以控制溶液pH的范围是8~12

D:向1 L 1 mol·L1ZnCl2溶液中加入NaOH固体至pH=6,需NaOH 0.2 mol

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D

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I was in the fifth grade and about to take a Maths test. In the first grade I had always been good at school, and simple Maths was easy for me and I always did well on tests. When it came to the fifth grade Maths, I couldn't understand it no matter how hard I tried. Mom and Dad had always been so proud of my good grades and I didn’t want to let them down. Just before the test, I had written several of the answers on my desk. I sat nervously as the teacher started to hand out the test papers. I didn’t want to get caught,but I didn't want to fail the exam either. .

As the teacher was walking around me, suddenly the fire alarm went off. It was an unscheduled fire drill (消防演习). We all rushed to the playground and stood together. As I stood in the warm sunshine, I realized what a fool I had been. I knew my mom and dad would be proud of me and love me no matter what my grades were. As soon as we were allowed to go back to the classroom, I walked to my desk and wiped (擦) the answers away. I had been given a second chance and I wasn’t going to waste it. I took the test, did my best, and felt at peace. I don’t remember what my grade was but that day has stayed in my heart and mind ever since.

I am not sure why God gave me a second chance that day. Life is foil of second chances, but you have to be willing to take them. You have to be willing to correct your mistakes. You have to be willing to follow your heart. Every day when you wake up, you are given a second chance in life.