问题
选择题
根据化学方程式A+NaOH═B+H2O推断，B，A的相对分子质量相差（ ）
A．12
B．18
C．22
D．40
答案
根据质量守恒定律，A的相对分子质量加上氢氧化钠的相对分子质量等于B的相对分子质量加上水的相对分子质量，A+40═B+18，故B、A的相对分子质量之差为：B-A═40-18═22．
故选C．
搜题请搜索小程序“爱下问搜题”
根据化学方程式A+NaOH═B+H2O推断，B，A的相对分子质量相差（ ）
A．12
B．18
C．22
D．40
根据质量守恒定律，A的相对分子质量加上氢氧化钠的相对分子质量等于B的相对分子质量加上水的相对分子质量，A+40═B+18，故B、A的相对分子质量之差为：B-A═40-18═22．
故选C．
Once a small boy lived on the farm which seemed so far away from everywhere. He needed to get up sunrise every morning to help his father on the farm. During sunrise he would and climb up on the fence(篱笆) along the side of the farm. He could see a house with golden windows. “ If they could golden windows, then there must be other nice things inside the house.” He how great it would be to live there. Then he himself, “ Some day I will go there and see this wonderful place.” One morning his father would go to town told him to stay at home for a rest. Knowing that this was his , he took a sandwich and headed across the field the house with the golden windows. As the afternoon went on, he began to realize how he was. The house was much farther than he had expected. As he went near the house, he saw golden windows but instead a place in bad of painting. A small girl very close to his came out of the poor house and stood by the broken fence. He asked her she had seen the house with the golden windows. The girl said,” Sure, I know,” and invited him to sit on the porch(门廊). As he sat there, he looked back from he just came. There he saw the turned the windows of his house to gold! Now he understood that everyone had his own house with golden windows.
|