问题 选择题

某种混合气体中可能含有N2、HCl、CO中的一种或几种,为确定该混合气体的成分,将混合气体依次通过NaHCO3溶液和灼热的Fe2O3,气体体积无变化但是有黑色物质生成;再通过NaOH溶液,气体体积明显减小;将燃着的木条伸入装有剩余气体的集气瓶中,木条熄灭(假设每步反应都是完全的),则下列说法中正确的是(提示:气体的分子数之比等于体积比)

A.一定有CO和HCl,肯定无N2

B.一定有CO和N2,可能有HCl

C.一定有CO和HCl,可能有N2

D.一定有CO和N2,肯定无HCl

答案

答案:B

题目分析:氯化氢溶于水会形成盐酸,而盐酸能与碳酸氢钠反应,生成二氧化碳气体,且一体积的氯化氢溶于水会反应生成一体积的二氧化碳,气体体积基本不变,故氯化氢气体可能存在;气体通过灼热的氧化铁,有黑色的物质析出,再通过NaOH溶液,气体体积明显减小,故一定存在一氧化碳;剩余的气体会使燃着的木条熄灭,一定存在氮气,所以一定存在一氧化碳和氮气,可能存在氯化氢气体。故选B

点评:在解此类题时,首先要根据题中的现象确定存在或不存在的物质,特别要注意气体反应会生成气体的,要比较反应前后的体积变化。

阅读理解

Everyone knows the story of Benjamin Franklin’s famous kite flight. He was a man of many talents and interests. His natural curiosity about things and the way they work made him try to find ways to make them work better. Although he made important discoveries and advancements, Ben didn’t “invent” electricity. He did, however, invent the lightning rod which protected buildings and ships from lightning damage.

In colonial America, most people warmed their homes by building a fire in a fireplace even though it was kind of dangerous and used a lot of wood. Ben figured that there had to be a better way. His invention of an iron furnace stove allowed people to warm their home less dangerously and with less wood. The furnace stove that he invented is called a Franklin stove. Interestingly, Ben also established the first fire company and the first fire insurance company in order to help people live more safely.

As the postmaster, Ben had to figure out routes for delivering the mail. He went out riding in his carriage to measure the routes and needed a way to keep track of the distance. He invented a simple odometer and attached it to his carriage.

In his old age, Ben retired from business and public service and wanted to spend his time reading and studying. He found, however, that his old age had made it difficult for him to reach books from the high shelves. Even though he had many grandchildren to help him, he invented a tool called a long arm to reach the high books. The long arm was a long wooden pole with a grasping claw at the end.

Later, other famous inventors, like Thomas A. Edison and Alexander Graham Bell, would follow in Ben’s footsteps by trying to find ways to help people live better. Today’s curious thinkers are keeping Ben’s traditions alive by inventing new and improved ways to make things work.

68. We can learn from the passage that Benjamin Franklin ___________________.

A. made his first invention using a kite

B. made his living by delivering the mail

C. set up some companies to help people to live better

D. made a stove which used other fuels instead of wood

69. The underlined word “odometer” in Paragraph 3 refers to something that ________.

A. contains the mail                                                 B. shows the direction

C. makes the carriage go fast                    D. records total miles covered

70. Benjamin Franklin invented a long arm in order to _________.

A. replace his disabled arm

B. play games with his grandchildren

C. get books from the bookshelf more easily

D. clean and tidy his house and the bookshelf

71. The last paragraph mainly wants to tell us that _____________.

A. Ben was the most famous inventor.

B. other inventors learned a lot from Ben.

C. Ben’s spirit of inventing remain with us.

D. thinkers are more likely to become inventors

单项选择题