问题 选择题

离子方程式CO32-+2H+═H2O+CO2↑中CO32-的代表的物质可以是(  )

A.CaCO3

B.NaHCO3

C.Na2CO3

D.BaCO3

答案

离子方程式CO32-+2H+=H2O+CO2↑中CO32-的代表的物质可以是易溶于水的碳酸盐.

A、碳酸钙是白色难溶于水的沉淀,故A错误;

B、碳酸氢钠是易溶于水的碳酸氢盐,拆成钠离子和碳酸氢根离子,故B错误;

C、碳酸钠是易溶于水的碳酸盐,故C正确;

D、碳酸钡是白色难溶于水的沉淀,故D错误.

故选C.

阅读理解

阅读理解。

     Parents are often amazed at how fast their child grows and develops. New research has determined

that the ability to quantify may develop much sooner than most parents realize.

     Kristy vanMarle, professor of the University of Missouri, has determined that contrary to what

previous studies have shown, infants (婴儿)are able to quantify substances (物质)-like sand or water-as

early as 10 months. As long as the difference between the two substances is large enough, infants will

choose the larger amount, especially when it comes to food.

     With the assistance of her team researchers, vanMarle tested the quantifying skills of babies by

presenting them with two cups: one containing a small amount of food, and one containing a larger

amount. Consistently, the babies chose the larger amount.

     "Several studies throughout the last 15 years have shown that infants are very good at telling how

many objects they see; however, infants don't seem to count things like water or sand," vanMarle said.

"What we're saying is that they can quantify substances; it's just much harder. The infants can see how

much food goes into each cup and compare that in their memories. They decide which amount is larger,

and they almost always select the larger one."

     This information further refutes (驳斥) the long-held idea that babies "know nothing of the world,"

vanMarle said.

     "Since psychologists have begun studying infants with sensitive measures, we've discovered a lot of

early abilities. I think for parents, it should be exciting to know that there's somebody in there that has

some fundamental and basic knowledge of the world, and that knowledge is guiding their development,"

vanMarle said.

     In the future, vanMarle says this kind of study could be linked to a child's progress in math-related

skills, although programs marketed to increase those abilities, such as "Baby Einstein," still have mixed

reviews when it comes to academic study.

1. The quantifying ability refers to the ability to     ___.

A. choose between different substances

B. get much knowledge of the world

C. describe the quantity of something

D. obtain math-related skill

2. What is mainly talked about in Paragraph 4?

A. The process of doing research.

B. The scientific findings.

C. The final choice of infants.

D. The observation of infants' behavior.

3. We can learn from the text that     .

A. some parents don't care about their kids

B. people used to think the world is known to babies

C. little research has been done on infants

D. some scholars disagree on baby-training programs

4. What's the best title of the text?

A. Breakthrough in Baby Studies

B. Amazing Baby-training Ideas

C. Early Human Abilities

D. Unique Quantifying Methods

单项选择题