问题 选择题

化学科学中最有创造性的工作就是设计和制备新物质,为人类造福.例如,尽管柠檬酸(C6H8O7)存在于一些水果中,但现在用作食品添加剂的柠檬酸大多数是人造的.下列有关柠檬酸的说法错误的是(  )

A.柠檬酸属于有机物

B.柠檬酸是由碳、氢、氧三种元素组成的

C.柠檬酸中碳、氢、氧三种元素质量比为6:8:7

D.柠檬酸的水溶液pH<7

答案

A、根据含有碳元素的化合物叫有机化合物,简称有机物.碳的氧化物、碳酸盐、碳酸虽含碳,但其性质与无机物类似,因此把它们看作无机物.由此可判断柠檬酸(C6H8O7)属于有机物;故A正确;

B、根据柠檬酸的化学式 C6H8O7 可知柠檬酸是由碳、氢、氧三种元素组成;故B正确;

C、根据化合物中各元素质量比=各元素的相对原子质量×原子个数之比,可得柠檬酸中碳、氢、氧三种元素质量比为:(12×6):8:(16×7)=9:1:14;故C错误;

D、根据酸溶液一定呈酸性,其溶液pH<7,因此柠檬酸的水溶液pH<7,故D正确;

故选C.

阅读理解

阅读理解。正确的写“T”,错误的写“F”。

      A woman saw three old men sitting in her front yard. She said, "I don't think I know you, but you

 must be very hungry. Please come in and have something to eat."

     "We don't go into a house together," they replied.

     "Why is that?" she asked.

     One of the old men answered. "His name is Wealth, this is Success, and I am Love." Then he said,

 "Now go in and discuss with your family which one of us you want in your house."

     Then the woman went in and told her family what was said. She said "Let's invite Wealth. Let him come

  in and bring us nice things. We have been so poor. "His husband disagreed, "My dear why don't we invite

 Success? Don't you want me to be a successful man?" Then the daughter asked, "Would it be better to

 invite Love? Our life will then be filled with 1ove!" "Let's take our daughter's advice (建议),"said the

 father and mother.

     So the woman went out and asked, "Which one of you is Love? Please come in and be our guest.

 "Love got up and started walking toward the house.The other two also got up and followed him.

 Surprised, the lady asked Wealth and Success, "I only invited Love. Why are you corning along? " The

  two o1d men answered, "If you had invited Wealth or Success, two of us would have stayed out,but

 since you have invited Love, wherever he goes, we go with him. Where there is Love. there is Wealth and

  Success."

1. This is a true story that happened a long time ago.

2. Wealth could make the family very rich.

3. The family had different ideas and didn't know whom to invite.

4. The three old men all went into the house to get something to eat.

5. The story tells us that 1ove is the most important of all.

单项选择题