题目

工业上利用高温分解石灰石（主要成分CaCO3，杂质不参与任何反应），得到生石灰．现实验室利用此原理来分析石灰石的纯度，使用100g原料，完全分解后得到固体64.8g，计算： （写出计算过程） （1）反应中得到的二氧化碳气体的物质的量为多少摩尔？ （2）原料中的碳酸钙纯度为多少？ 答案：【考点】根据化学反应方程式的计算． 【专题】有关化学方程式的计算；有关化学方程式的计算． 【分析】由质量守恒定律，固体物质减少的质量均为生成二氧化碳的质量，由反应的化学方程式计算出石灰石中碳酸钙的质量，进而计算出石灰石样品中CaCO3的质量分数． 【解答】解：由质量守恒定律，Even before my father left us, my mother had to go back to work to support our family. Once I came out of the kitchen, complaining, “Mom, I can’t peel(剥……的皮) potatoes. I have only one hand.”Mom never looked up from sewing. “You get yourself into that kitchen and peel those potatoes,” she told me. “And don’t ever use that as an excuse for anything again!”In the second grade, our teacher lined up my class on the playground and had each of us race across the monkey bars, swinging from one high steel rod to the next. When it was my turn, I shook my head. Some kids behind me laughed, and I went home crying.That night I told Mom about it. She hugged me, and I saw her “we’ll see about that” look. The next afternoon, she took me back to school. At the deserted playground, Mom looked carefully at the bars.“Now, pull up with your right arm,” she advised. She stood by as I struggled to lift myself with my right hand until I could hook the bar with my other elbow(肘). Day after day we practiced, and she praised me for every rung I reached. I’ll never forget the next time, crossing the rungs, I looked down at the kids who were standing with their mouths open.One night, after a dance at my new junior high, I lay in bed sobbing. I could hear Mom come into my room. “Mom,” I said, weeping, “none of the boys would dance with me.”For a long time, I didn’t hear anything. Then she said, “Oh, honey, someday you’ll be beating those boys off with a bat.” Her voice was faint. I peeked(窥视) out from my covers to see tears running down her cheeks. Then I knew how much she suffered on my behalf（利益）. She had never let me see her tears.小题1: Which of the following expressions can be used most suitably to describe Mom’s attitude when she made the child to peel potatoes?A．Cruel. B．Serious.C．Cold. D．Strict小题2: What does the sentence “I saw her ‘we’ll see about that’ look” imply(暗示)?A．Mom believed every aim could be achieved if you stuck to it.B．The race across monkey bars was not difficult enough for a child to give up.C．Mom was determined to prove she herself was better than the teacher.D．What the child had said brought Mom great attraction and curiosity.小题3: When the child looked down at the kids, they were standing with their mouths open because _________.A．they felt sorry for what they had done beforeB．they were afraid the author might fall off and get hurtC．they were astonished to find the author’s progressD．they wanted to see what the author would do on the bars小题4:The most probable conclusion we can draw after reading the passage is ______.A．the last incident was sad enough to make Mom weepB．the child’s experience reminded Mom of that of her ownC．Mom could solve any problem except the one in the last paragraphD．in fact Mom suffered more in the process of the child’s growth