通常人们把拆开1mol某化学键所吸收的能量看成该化学键的键能。键能的大小可以衡量

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问题:

通常人们把拆开1 mol某化学键所吸收的能量看成该化学键的键能。键能的大小可以衡量化学键的强弱池可用于估算化学反应的反应热(△H),化学反应的△H等于反应中断裂旧化学键的键能之和与反应中形成新化学键的键能之和的差。

请回答下列问题:   

(1)比较下列两组物质的熔点高低(填“>”   或“<”)。 SiC____Si;SiCl4____SiO2。   

(2)工业上高纯硅可通过下列反应制取:SiCl4(g)+2H2(g)Si(s)+4HCl(g) 该反应的反应热

△H=___________kJ/mol。

考点:化学键与化学反应中能量变化的关系
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How to protect children Web fans from unsuitable material on-line while encouraging them to use the Internet has long been discussed in the US.
For some parents, the Internet can seem like a jungle, filled with danger for their children. But jungles contain wonders as well as dangers and with good guides, some education, and a few precautions, the wilds of the Internet can be safely navigated. "Kids have to be on-line. If we tell our kids they can’t have access to the Internet, we’re cutting them off from their future, " said an expert.
Most kids have started to use search engines. Many of them are great for finding tons of interesting Internet sites, and they can also locate places where you might not want your kids to go. There are search engines designed just for kids. A certain software contains only sites that have been selected as safe. The most popular way to limit access would be to use what is known as a "content screener". But this can’t be wholly reliable, and the best thing parents can do is to talk to their kids and let them know what is OK or not OK to see or do on the Internet. Another way is that mum or dad is nearby when the child is surfing the Internet.
A few other tips
·Don’t put the PC in a child’s room but keep it in an area where mum or dad can keep an eye on things. That also makes the Internet more of a family activity.
·Ask your child what he or she has been doing and about any friends they make on-line.
·Tell your child not to give on-line strangers personal information, especially like address and phone number.
·And tell your children never to talk to anyone they meet on-line over the phone, send them anything, accept anything from them or agree to meet with them unless you go along.

Which of the following is right according to the passage

A. Surfing the Internet is the best method of educating children.
B. Children’s not having access to Internet may have effect on their progress.
C. Using a content screener is most reliable for keeping children having access to Internet.
D. Searching engines can help children to select materials fit for them.

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下列哪种属于均匀性肥胖()。

A.男性型肥胖

B.普遍型肥胖

C.臀型肥胖

D.内脏型肥胖

E.女性型肥胖

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下列关于脊髓的描述错误的是()。

A.由灰质和白质构成

B.中间带是指中央管周围的区域

C.前角主要由运动神经元组成

D.后角主要由中间神经元组成

E.白质位于脊髓灰质周围

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依据《安全生产法》的规定,涉及生命安全、危险性较大的特种设备的目录由国务院负责特种设备安全监督管理的部门制定,报( )批准后执行。

A.政府

B.特种设备管理部门

C.国务院

D.国家安全监督管理部门

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营养性缺铁性贫血肝肾阴虚证应首选

A.大补阴丸合茜根散
B.归脾汤
C.大补元煎
D.犀角地黄汤
E.左归丸

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