问题 实验题

同学们在学完酸的化学性质后,做了如下实验:

同学们观察到A试管中有(1)_________现象。实验结束,同学们依次将A、B试管中的废液缓慢倒入同一洁净的废液缸中,观察到废液显红色。为了科学处理实验后产生的废液,同学们决定对废液缸中废液的溶质成分(不考虑石蕊)进行探究。

【查阅资料】钡离子有毒。

【提出问题】最终废液中含有什么溶质?

【猜想与假设】甲同学猜想:废液中只含有HCl一种溶质

乙同学猜想:废液中含有HCl、BaCl2两种溶质

丙同学的猜想:(2)____________________。

【表达与交流】甲同学猜想的理由是(3) __________________________________。

【活动与探究】同学们为了验证以上猜想,继续进行实验:

甲同学:取少量废液于试管中,滴加少量的氯化钡溶液,未观察到明显现象。

乙同学:取少量废液于试管中,滴加少量的碳酸钠溶液,看到产生气泡。

丙同学:取少量废液于试管中,滴加少量的硫酸钠溶液,看到产生白色沉淀。

【结论与应用】通过分析甲、乙、丙三位同学们的实验及现象,最终确认(4)______(填甲、乙、丙)猜想正确,你认为处理该废液的方法是(5)_________________。

答案

(1)产生白色沉淀

(2)HCl、H2SO4

(3)硫酸与氯化钡恰好完全反应生成HCl

(4)乙

(5)向废液中滴加硫酸钠溶液至不再产生白色沉淀,向废液中加氢氧化钙(氢氧化钠)溶液至红色变紫色,可倒掉(其他答案合理给分)

选择题
阅读理解

Everyone hates to wait in lines. We get that anxious feeling that our precious life is slipping away while we’re doing something so meaningless. But it’s not always the length of the wait we find so unbearable. Some people camp outside Apple stores for an entire night just to get their hands on the latest product. But waiting 10 minutes in a grocery store just to buy a drink? Forget it.

Our behavior when waiting is only partly decided by the length of the wait. “Often the psychology of queuing is more important than the statistics of the wait itself,” notes the MIT researcher Richard Larson.

One apparent aspect of queuing psychology is that we get bored when we wait in line. This issue is solved in many ways, from magazines in hospital waiting rooms to mirrors in elevators so that we can check our appearance.

We really hate it when we expect a short wait and then get a long one. But studies show that we are much more patient when we are given an idea of how long we’ll be waiting.

Walt Disney Co knows this better than anyone else. It posts estimated waiting times for attractions in its theme parks. But according to Larson, these times are overestimated so that visitors get to the front of the queue more quickly than they expect. It keeps them happy.

But perhaps the biggest influence on our feelings about waiting in a line has to do with our sense of fairness. When it comes to queues, the universally acknowledged standard is first come, first served. Any departure from this principle is regarded as unfair and can lead to violent queue anger.

You’ve probably experienced mild queue anger yourself in fast food restaurants, watching people in the other line zoom ahead of you, cursing yourself for having chosen the “wrong” line. In order to solve this problem, the serpentine(蛇形) line was invented. The serpentine line guides all customers into one big snaking queue, separated by ropes or barriers. When you reach the head of the queue, you are directed to the next available server, or teller, or customs official. The serpentine line isn’t always faster than multi-lines before an array(排) of cash registers. But it offers important comfort: you absolutely never have to see someone arrive after you and get served before you.

In life, waiting is inevitable. But a better understanding of the psychology of waiting can help make it a bit more bearable. When all else fails, bring a book or a smart phone will also do.

小题1:In the 1st paragraph, the author intends to tell us_____.

A.why people are crazy about Apple’s products

B.people waste their precious time in queuing

C.waiting time is not the only cause for people’s hate in queuing

D.the psychology is the real reason why people hate to wait in lines小题2:Walt Disney Co makes people queuing happily by_____.

A.having people queue in serpentine line

B.letting people know how long they will wait exactly

C.making people queue shorter than they are informed

D.offering people magazines to read when waiting in lines小题3:Serpentine line was invented to_____.

A.make the waiting line move faster

B.guarantee the first-come-first-served principle

C.solve the problem of feeling bored in queuing

D.guide all customers into one big snaking queue小题4:The main purpose of the passage is _____.

A.to explain the advantages of serpentine line

B.to introduce ways of saving time in queuing

C.to offer an explanation of the psychology of queuing

D.to analyze the psychology of people queuing for Apple products