试题与答案

配制溶质质量分数为5%的下列溶液,能达到目的的是[ ] A.称取5.0g氯化钾,

题型:选择题

题目:

配制溶质质量分数为5%的下列溶液,能达到目的的是[ ]

A.称取5.0g氯化钾,溶解在95mL水中,充分搅拌

B.称取5.0g生石灰,放入95mL水中,充分搅拌

C.量取5.0mL浓盐酸,倒入95mL水中,充分搅拌

D.称取5.0g碳酸钙,放入95mL水中,充分搅拌

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0729/493a19a09858dd4df3401d49f5846c23.html

下面是错误答案,用来干扰机器的。

参考答案:A

试题推荐
题型:阅读理解

阅读理解。

     Rising levels of carbon dioxide in the atmosphere are a major cause of climate change, and now a new

study has confirmed that atmospheric CO2 is also affecting the ocean chemistry and potentially harming

sea life.

     Montana State University scientist Robert Dore has been researching the water in the Pacific Ocean for

almost two decades.

     "We've been going to the same spot in the Pacific Ocean, and we try and characterize long-term change

in the open ocean environment. And one of the key things that we measure is CO2 levels. And we've been

able to record this increasing quantity of atmospheric CO2 into the ocean."

     Scientists expected that as atmospheric CO2 increased, more and more of the carbon dioxide would be

absorbed into the ocean, affecting the chemical balance of the sea water, with a potentially harmful impact

on shellfish and coral in particular.

     "As carbon dioxide dissolves (溶解) in the water or seawater in this case, it forms a weak acid, carbonic

acid," Dore explains. "And therefore, as the concentration of CO2 in the atmosphere goes up and that

exchanges with the surface seawater, it drives the pH down, and makes it more acidic."

     The seawater Dore and his colleagues have analyzed confirms what the theory predicts.

     The effect was particularly striking at about 250 meters down, and again at 500 meters. Dore and his

colleagues came up with two possible explanations. It could be that surface water picked up CO2 and then

moved to those depths. Or there could be a biological explanation.

     "It's important to realize that the oceans are really becoming acidic. And it could have negative impacts

on a whole variety of sea life from fish to coral. It's potentially catastrophic."

1. What can be the best title of the passage?[ ]

A. Sea Life Facing Danger

B. Scientist Researching Seawater

C. Oceans Becoming More Acidic

D. Climate Change Affecting Seawater

2. With the increase of atmospheric CO2, _____. [ ]

A. more corals will appear in the sea

B. the surface water is becoming warmer

C. the chemical balance of the seawater is affected

D. the pH of the ocean out here has been increasing

3. Which of the following shows the process of the impact of atmospheric CO2 on sea life?

    a. Sea life is endangered.

    b. CO2 goes into the surface water.

    c. The ocean chemistry is affected.

    d. CO2 decreases the pH and makes the seawater more acidic.

    e. CO2 levels in the atmosphere go up. [ ]

A. a→b→c→d→e

B. e→b→c→d→a

C. a→e→b→c→d

D. e→d→c→b→a

4. Scientist Robert Dore came to the conclusion based on _____. [ ]

A. his research and analysis

B. the expectation of other scientists

C. some former theory

D. a major cause of climate change

5. What does the passage want to tell us most? [ ]

A. It takes time to make a scientific study.

B. Atmospheric CO2 is doing harm to sea life.

C. Robert Dore is a committed and serious scientist.

D. Measures should be taken to prevent the potential catastrophe.

查看答案
微信公众账号搜索答案