问题 选择题

下列物质的水溶液只存在溶质分子的是(    )

A.HCl

B.CH3COOH

C.蔗糖

D.Na2CO3

答案

答案:C

题目分析:水溶液只存在溶质分子,说明该溶质是不能电离的,属于非电解质,HCl、醋酸和碳酸钠都是电解质,在溶液中可以电离,蔗糖是非电解质,所以正确的答案选C。

点评:该题是中等难度的试题,试题灵活性强,注重能力的培养和训练。有利于培养学生的逻辑思维能力和创新思维能力,以及答题的灵活应变能力。

阅读理解
阅读理解

In Egyptian myth, Apophis was the ancient spirit of evil and destruction, a demon (恶魔) that was determined to throw the world into darkness forever. A fitting name, astronomers reasoned, for a threat now rushing towards Earth from outer space. Scientists are monitoring the progress of a 390-metere wide asteroid (小行星) discovered last year, which is potentially on a collision (碰撞)course with the planet.

NASA has estimated that Apophis has an outside chance of hitting the Earth in 2036. If it did hit us, thousands of square kilometers would be directly affected by the explosion but the whole of the Earth would see the effects of the dust sent into the atmosphere. At a recent meeting of experts in Near-Earth objects (NEOs) in London, scientists said it could take decades to design, test and build the required technology to deflect the asteroid.

The Apophis asteroid is placed at four out of ten on the Torino scale—a measure of the threat caused by an NEO where 10 is a certain collision which could cause a global disaster. This is the most possible danger of any asteroid in recorded history and it has a 1 in 37 chance of hitting the Earth.

Alan Fitzsimmons, an astronomer from Queen’s University Belfast, said, “When it does pass close to us on April 13, 2029, the Earth will deflect it and change its orbit. There is a small possibility that if it passes through a particular point in space, the so-called keyhole, the Earth’s gravity will change things so that when it comes back around again in 2036, it will collide with us.” The chance of Apophis passing through the keyhole, a 600-meter patch of space, is 1 in 5,500, based on current information.

There is no shortage of ideas on how to deflect asteroids. The Advanced Concepts Team at the European Space Agency has led the effort in designing a range of satellites and rockets to nudge asteroids that are on a collision course for Earth into a different orbit.

小题1:The best title for this passage would be ___________.

A.Apophis Asteroid, a Possible Destroyer of Earth

B.Apophis, a Good Name for Dangerous Asteroid

C.Our Planet Will Be Ruined in 2036

D.Scientists Study Apophis Asteroid小题2:The name Apophis mentioned in the passage indicates that the asteroid is _________.

A.powerful

B.mysterious

C.boring

D.destructive小题3:The underlined word “deflect” in Paragraph 2 probably means _________.

A.destroy the quality of

B.change the direction of

C.measure the size of

D.look into the truth of小题4:Which of the following is NOT true?

A.If Apophis hit the earth, its impact would be enormous.

B.No way to deal with Apophis is available at present.

C.Apophis is the first dangerous asteroid in recorded history.

D.It is uncertain whether Apophis will hit the earth in 2036.小题5:What would the passage talk about if it continued?

A.An Egyptian myth about Apophis.

B.NASA’s study on NEOs.

C.How the keyhole influences Apophis.

D.What methods can be used to deflect the asteroid.