问题 选择题

下列化学反应的离子方程式正确的是(  )

A.将少量金属钠放入冷水中:Na+2H2O=Na++2OH-+H2

B.将铝片加入烧碱溶液中:2Al+2OH-+2H2O=2AlO2-+3H2

C.FeI2溶液中通入少量氯气:2Fe2++Cl2=2Fe3++2Cl-

D.向澄清石灰水中通入过量二氧化碳:Ca2++2OH-+CO2=CaCO3↓+H2O

答案

A、反应电荷不守恒,应为:2Na+2H2O=2Na++2OH-+H2↑,故A错误;

B、金属铝能和烧碱反应生成氢气,原理是:2Al+2OH-+2H2O=2AlO2-+3H2↑,故B正确;

C、亚铁离子和碘离子还原性强弱顺序是:I->Fe2+,少量的氯气会先将碘离子氧化,即2I-+Cl2=2Cl-+I2,故C错误;

D、向澄清石灰水中通入过量二氧化碳会生成可溶的碳酸氢钙,离子反应为:OH-+CO2=HCO3-,故D错误.

故选B.

单项选择题 A3/A4型题
阅读理解

I do a lot of hiking.And I can step out of my house and within minutes reach a beautiful forest where I walk for exercise every day.I see many photography subjects such as parrots,snakes,hares,big trees and flowers.There are so many different flowers around my place that once I decided to see how many types I could count in a one­hour­long walk,and I counted over 100.

Needless to say,as a keen amateur photographer,I always take a camera with me.I have three favorites: a Pentax Optio RZ10,a Sony Alpha 390 and a Panasonic Lumix FZ100.I mostly take the Pentax pocket camera with me.This Pentax pocket camera takes images as good as those from much more expensive Single Lens(镜头)Reflex cameras.It allows you to get to just 1 cm from the subject,and these images are of astonishing clarity(清楚).I can stick the camera right into a flower.And the photo shows fantastic details.

The Pentax is also good at taking landscapes.The color is natural and price again the details even of distant objects are great.Sometimes,even when I have one of my other cameras with me,I still just use the Pentax pocket camera.About half of all the images on my website were taken with the Pentax.

The Pentax takes quality images in poor light and the zoom works well.You have to work hard to get a blurry(模糊的)shot.This is an especially good feature at parties and gatherings.You get fantastic photos of people.You don't have to wait for them to keep still.

Keep this camera in your pocket or in the car.It takes up little room;it's light and you'll never regret it!

小题1:Why does the author walk through the beautiful forest every day?

A.He takes exercise to keep fit.

B.He goes there to count flowers.

C.He takes photos in the forest.

D.He goes to see photography subjects.小题2:Which of the following cameras did the author use most?

A.The Sony Alpha 390.

B.The Pentax Optio RZ10.

C.The Panasonic Lumix FZ100.

D.The Single Lens Reflex camera.小题3:We can infer from the passage that________.

A.the author is a professional photographer

B.the author took blurry photos at gatherings

C.the author has put half of his photos on his website

D.it is good to take a quick photo with the Pentax小题4:In the last paragraph the author advised us to________.

A.buy a very small camera

B.take photos of our friends

C.keep a Pentax at hand

D.take photos wherever we are