试题与答案

甲数的60%和乙数的60%一定相等.______.(判断对错)

题型:解答题

题目:

甲数的60%和乙数的60%一定相等.______.(判断对错)

答案:

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按中考评分标准给分 “________ 又回来了”或“从此,我又找回了 ”都是半命题作文。学生写作时,应根据自己的实际情况进行补题,补题要求,选择一个较为新颖的写作角度,体现更为深刻的思想价值;选择较...

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( )5. A. something  
( )6. A. quieter  
( )7. A. much      
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( )10. A. can't  
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B. her        
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C. little    
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C. me          
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D. to hear          
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题型:问答题

某化学小组模拟“侯氏制碱法”,以NaCl、NH3、CO2和水等为原料以及图1所示装置制取NaHCO3,反应的化学方程式为:

NH3+CO2+H2O+NaCl=NaHCO3+NH4Cl.然后再将NaHCO3制成Na2CO3

(1)装置乙的作用是______.为防止污染空气,尾气中含有的______需要进行吸收处理.

(2)由装置丙中产生的NaHCO3制取Na2CO3时,需要进行的实验操作有______、洗涤、灼烧.

(3)若在(2)中灼烧的时间较短,NaHCO3将分解不完全,该小组对一份加热了t1min的NaHCO3样品的组成进行了研究.取加热了t1min的NaHCO3样品29.6g完全溶于水制成溶液,然后向此溶液中缓慢地滴加稀盐酸,并不断搅拌.随着盐酸的加入,溶液中有关离子的物质的量的变化如图2所示.则曲线c对应的溶液中的离子是______(填离子符号);该样品中NaHCO3和Na2CO3的物质的量之比是______.

(4)若取10.5gNaHCO3固体,加热了t1min后,剩余固体的质量为7.4g.如果把此剩余固体全部加入到200mL1mol/L的盐酸中,则充分反应后溶液中H+的物质的量浓度为______(设溶液体积变化忽略不计).

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