搜题请搜索小程序“爱下问搜题”
问题 问答题

某溶液中含n个Fe3+、n个NO3-、m个Cl-，还存在H+或OH-，此外再无其它离子存在．由此可推知该溶液呈______性．（选填“中”“酸”或“碱”）

答案

由于题目中n、m数值无从判断，所以无法从溶液电中性来推断．由信息可知溶液中含Fe3+、NO3-、Cl-，则溶液中一定不存在OH-，因为OH-和Fe3+相结合生成Fe（OH）3沉淀，所以溶液中一定存在H+故溶液显酸性．

故答案为  酸

完形填空

短文填空。从下面方框中选出10个单词，用它们的适当形式填入短文空格内，使短文意思正确、通顺 (每词限用一次)。(共10小题，每小题1分；计10分)

before; other; think; teach; wind; hope; stay; say; something; good; after; take

Bill is a good student but he doesn't like to use his head. He often says something without ___小题1:__. It makes__小题2:__ unhappy. Mr. Green was a teacher in a school. He's old and doesn't work now. He likes children. He often gives Bill some fruit or cakes and ___小题3:__ him to read and write. So he likes the old man very much.

It was a___小题4:_ Saturday, and Bill didn't go to school. He had some questions and __小题5:to ask Mr. Creen, but he couldn't find him. Mother said. “Mr. Green isn’t __小题6:__ at home now. He is ill in hospital. I will go and see him_小题7:__ breakfast. “Bill wanted to go there with his mother. But his mother didn’t agree. She said, “You are not a good boy. I can't take you there. "

“Don’t worry, mum. I am sure I will not do that. "

Then they went out with some flowers. They _小题8:__a taxi to the hospital. In the hospital, Bill didn’t say ___小题9:___ at first. When they wanted to leave, he comforted the old man and said,”You look ___小题10:___, I think. The doctors say you are going to die, but I don’t think they are right. ”
查看答案
选择题

一学生用100N的力将质量为0.5千克的球以8米/秒的初速度沿水平方向踢出20米远，则学生对球做的功为（　　）

A．2000J

B．16J

C．1000J

D．无法确定
查看答案