问题 选择题

等体积、等物质的量浓度的硫酸、氢氧化钠溶液分别放在甲、乙两烧杯中,各加入等质量的铝,生成氢气的体积比为5:6,则甲、乙两烧杯中的反应情况可能分别是(  )

A.甲、乙中都是铝过量

B.甲中铝过量,乙中碱过量

C.甲中酸过量,乙中铝过量

D.甲中酸过量,乙中碱过量

答案

发生反应有:2Al+3H2SO4═Al2(SO43+3H2↑;2Al+2NaOH+2H2O=2NaAlO2+3H2↑,

讨论:(1)若酸碱均过量,则产生的氢气取决于铝,铝的质量相同,所以氢气相等1:1.

(2)若酸碱均不够,产生的氢气取决于酸碱,根据方程式,酸碱产生的比值为2:3

(3)现在的比值是5:6,比值处于 2:3和1:1之间,由于铝消耗硫酸量大于碱,此时铝对于酸过量而对于碱不足,

故选B.

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

How do you enter a room full of strangers? Do you walk right in full of confidence? Or do you try to slip in without being noticed? ___小题1:___

In life, we admire those who do their tasks confidently. We prefer people who appear to know what they are doing. But where does that confidence begin?

Developing self-confidence starts very early. It’s parents’ role to get kids on the right track toward becoming confident people. ___小题2:___ That can be done by focusing on the child’s strengths. Parents should encourage their children to try new things and take risks. When children make mistakes, their parents should still let them know that they are loved. Children whose parents do these things will likely develop into confident adults. ___小题3:___ So what’s the solution?

With most things in life, practice makes perfect, and that is true of confidence skills. ___小题4:__Always hold your head high and look people in the eye. Answer questions clearly and confidently.

Focus on the things that you do well, and look for opportunities to use those abilities.

Prepare thoroughly for every project. You’ll approach the task more confidently knowing that you are ready.

___小题5:___ It could be a good test score or a prize from a contest. Remind yourself that one success often leads to the next.

However, all humans fail at times, and you will too. Even with efforts to try all the above, you will never be perfect. But you can learn to love and accept yourself and live your life with confidence.

A.Keep in mind an item that reminds you of a recent success.

B.The more you practice them, the easier they will become.

C.The way you go into new situations show your level of self-confidence.

D.Our goal is to prepare students to go into the world with confidence.E. To help that process, parents should always offer more praise than criticism.

F. Learning from mistakes helps you face the same situation later without fear.

G. But self-confidence still doesn’t come easily.

选择题