下列措施一定能使反应速率加快的是（） A．增加反应物的物_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

下列措施一定能使反应速率加快的是（　　）

A．增加反应物的物质的量

B．升高温度

C．缩小容器体积

D．加入生成物

答案

A、增加反应物的物质的量，反应物的浓度不一定增加，如固体、纯液体，反应不一定加快，故A错误；

B、升高温度，增加单位体积内的活化分子数，有效碰撞增加，反应速率加快，故B正确；

C、缩小反应容器的体积，浓度不一定增加，如固体、纯液体，反应不一定加快，故C错误；

D、加入生成物，浓度不一定变化，如固体、纯液体，故D错误．

故选B．

问答题

Andrew is the owner of a bakery. There have been a number of burglaries in the vicinity of the bakery and he decided to install a security alarm system. He entered into a contract with Betta Security CC for the installation of the alarm. Andrew was requested to read and fill in a form confirming the order. The form contained a clause that ‘Betta Security CC accepts no liability whatsoever for any injury or loss sustained as a consequence of the wrongful installation or operation of any equipment supplied or fitted by it’.The installation of the alarm was carried out incorrectly. During the night the wiring short-circuited, which caused a fire that destroyed the bakery. Betta Security CC admits negligence but refuses to compensate Andrew for the losses sustained, relying on the exclusion clause.Required:Advise Andrew on the validity and consequences of the exclusion clause. (10 marks)

单项选择题 A1/A2型题

牙本质所含无机物约占重量的（）。

A.50％

B.60％

C.70％

D.80％

E.90％