题干

下列应用和相应的原理(用化学方程式表示)及基本反应类型正确的是(  )

选项

物质的应用

化学方程式

反应类型

A

电解水

2H2O22H2O+O2

分解反应

B

向烧碱溶液中通人CO2

2NaOH+CO2═Na2CO3+H2O

复分解反应

C

溶洞的形成

CaCO3+H2O+CO2═Ca(HCO32

化合反应

D

比较铜和银的活动性

Cu+AgNO3═Cu(NO32+Ag

置换反应

A:A

B:B

C:C

D:D

上一题 下一题 0.0难度 选择题 更新时间:2013-07-17 10:18:50

答案(点此获取答案解析)

C

同类题3

阅读下列短文,从每题所给的四个选项(A、B、C和D)中选出最佳选项。

    Is your TV connected to the Internet? What about your chair, or your fridge? Probably they are not. But in the future, most things in your home may be connected, thanks to the so-called "Internet of things".

    The Internet of things may be coming sooner than you think. Earlier this year, Samsung CEO spent a lot of time talking about the Internet things. He said that three years from now, every Samsung product will be part of the Internet of things, no matter whether it's a remote control or a washing machine.

    So, how do household objects that are part of the Internet of things work? Well, think of a common chair. When connected to the Internet, the chair warms up when it knows the user has just walked into the room and is feeling cold.

    An Internet-connected camera could help people feel safer in their homes. It can know people's faces and has an infrared sensor(红外传感器), so even if it's dark it can see when someone passes by and send you a message on your smart-phone to let you know who's there. If the person is someone you don't know, it can tell you that, too.

    But according to MIT Technology Review, whether companies are connecting dog food bowls or safety systems to the Internet, there may be some problems. For example, many early connected-home objects don't have much built-in security, which means they could be hacked(攻击). Moreover, it could be difficult to get these new machines to work together especially when they are made by different companies. To fight this, many companies have joined the Open Interconnect Consortium, which had 45 members by late 2015.

    So, picture this: you enter your home. The temperature changes to make you feel comfortable. Your favorite music starts playing for you. Do you think that this would be a good thing? It may happen sooner than you think.