题干

王村去年植树400棵,今年比去年多植树800棵,今年植树是去年的       倍. (   )

A:5

B:4

C:3

D:6

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答案(点此获取答案解析)

C

同类题1

在小英家的仓库里,堆放着一袋袋化肥一一碳酸氢铵( NH4HCO3).过了一个夏天,小英发现这种化肥所持有的刺激性气味变得更浓烈了,有些化肥袋里碳酸氢铵变少了,检查发现变少的化肥包装袋没有密封,化肥也没有撒落在地上,更没有人进过仓库开袋使用。

为了探究这些化肥减少的原因,小英在实验室取了一些碳酸氢铵粉末,放在蒸发皿中加热,过一会儿观察到粉末完全消失,同时也闻到了这种刺激性气味.粉末为什么会消失呢?

⑴【提出问题】碳酸氢铵粉末消失的原因是什么?

⑵【猜想】①碳酸氢铵粉末在不加热或加热条件下由固态变成它的气态。②碳酸氢铵在不加热或加热条件下发生分解反应,可能产生的物质有氨气和一些氧化物。

⑶【查阅资料】①碳酸氢铵属于氨肥,不具有升华的性质,说明上述猜想____ (填序号)不成立;②氨气(化学式NH3)具有特殊的刺激性气味,极易溶于水,其水溶液是碱性,但干燥的氨气不能使干燥的红色石蕊试剂变蓝;③NO2为红棕色气体。NO为无色气体,在空气中易发生反应:2NO+O2=2NO2

⑷【实验操作,现象与结论】

实验操作

实验现象

实验结论

①取适量碳酸氢铵于试管中加热,如图一所示,将干燥的红色石蕊试纸接近导管口

产生强烈的刺激性气味,试管壁上有无色液滴且试纸变蓝,但未见红棕色气体

分解产物中有____,没有____

②按如图二所示装置继续实验,直到反应完全

澄清石灰水变浑浊

分解产物中有____

⑸【应用】①利用氨气的化学性质,请写出实验室检验氨气的方法(写出实验操作、现象、结论):____

②如果你家里有碳酸氢铵化肥,你应该如何保存? ____

同类题3

阅读理解

    Cities are taking interest in electric scooter-share systems as an affordable transportation to cut down on pollution and traffic jams. The electric scooters, which weigh between 30 and 40 pounds, reach speeds of about 15 mph.

    In September 2017,Santa Monica, California, became the first U.S. city to have an electric scooter-share service. Users find and unlock one of the more than 1,000 scooters with a smartphone app. A ride costs $ 1,and then 0.15 cents for each minute of riding throughout the beach town.

    Bird, the startup operating the scooter-share, picks up the scooters every night to them, and places them around Santa Monica each morning ready for people's use. The company was created by Travis VanderZanden, who once worked in Uber and Lyft, after he realized ridesharing services failed to help with traffic jams and air pollution. Since its September 2017 beginning, Bird's system has served more than 50,000 riders who have taken 250,000 trips — more than half of which have been in the last month. It's since expanded (扩 张) to Venice, California, and some neighborhoods in Los Angeles and San Diego. Bird plans to expand to lots of markets by the end of 2018.

    Competitors, backed by millionaires, are appearing. Two bike-share startups LimeBike and Spin, have spoken of plans to provide electric scooters in cities this year.

    Electric scooters have also gotten the attention of Mayor Pete Buttigieg from South Bend,Indiana. The city is interested in using them as a way to improve public transportation. South Bend was one of the first to use bike-share systems, which allow people to park ridesharing bikes on public land. “We love to be early pioneers,” said Buttigieg. “If we work out the safety problem, we would be open to welcoming the technology.”

    “We need to make sure these new transportation systems are lawful and safe for users,”Constance Farrell,a spokeswoman for the city of Santa Monica told CNN. “We would like to see electric scooters continue to operate in the city. They are in line with our goal of multi-modal living and carbon-light living. ” According to Farrell,there have been eight accidents, including one with a serious head injury, in Santa Monica after the scooters rolled out. Users are required to have a driver's license (驾 照),shouldn't ride on sidewalks or have other passengers on board.

    Bird has given out free helmets to some riders and tells its users to ride in bike lanes, but some users ride on sidewalks, and most U.S. streets don't have bike lanes.

    “The global community of cities is going to have to work this all out for scooters,”Buttigieg said. “They can move unbelievably quickly. That's exciting,and a little dangerous. ”