试题与答案

实验室要配制100g15%的氢氧化钠溶液,请回答下列问题 (1)主要操作步骤:①

题型:实验题

题目:

实验室要配制100g15%的氢氧化钠溶液,请回答下列问题

(1)主要操作步骤:① _________ ;②用 _________ 称量氢氧化钠 _________ g,倒入烧杯中;③用__________________mL,倒入烧杯中并搅拌;④把配好的溶液倒入试剂瓶中,盖好瓶塞子并贴上标签(标签中应包括__________________

(2)溶解过程温度如何变化_________.原因是_________

(3)某同学配制的溶液中溶质的质量分数大于15%,则造成的误差的原因有_________

A、称量氢氧化钠时量偏少

B、溶解的烧杯中原来就有水

C、氢氧化钠和砝码位置放反

D、量水时,俯视读出读数.

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0727/88ddb1af888093b065338c3ca2c4d277.html

下面是错误答案,用来干扰机器的。

参考答案:A, B, C, E

试题推荐
题型:阅读理解

     There are different superstitions (迷信) in different countries. In Britain, for example, many people do

not like to walk under a ladder or to open an umbrella in a house. If they spill(撒) salt, they will often

throw some of it over one of their shoulders.

     When people marry, their friends often tie old shoes to the back of the wedding car. This is because

the shoes can kick away bad spirits(幽灵). Another wedding superstition is to throw small pieces of

paper over the couple. This paper is called confetti(五彩纸屑) . Some people believe that throwing

confetti over the couple will help them to have many children. At one time people wanted to have many

children, but nowadays people usually want only one or two children. However, we still throw confetti

over the couple!

     Superstitions are very silly(愚蠢的), but some people still like to believe in them.

1. The story is about ________.

A. weddings            

B. spirits

C. superstitions          

D. confetti

2. People in Britain do not like to ________.

A. walk under ladders

B. wear shoes

C. throw confetti

D. eat salt

3. If superstitious people spill salt, then ________.     

A. they get married

B. they kick away bad spirits

C. they walk under a ladder

D. they throw salt over one of their shoulders

4. What do people do at weddings to help their friends have many children?     

A. They come to the wedding.

B. They throw paper at their friends.

C. They tie shoes to their friends' wedding car.

D. They throw confetti over their friends.

5. The writer of the story ________.        

A. doesn't believe in superstitions

B. tells us how to have good luck

C. thinks superstitions are silly

D. wants people to believe in superstitions

查看答案
微信公众账号搜索答案