题干

某研究性学习小组为了研究影响化学反应速率的因素,设计如下方案:

实验编号

0.01mol•L1酸性KMnO4溶液

0.1mol•L1H2C2O4溶液

1mol•L1MnSO4溶液

反应温度/℃

反应时间

2mL

2mL

0

0

20

125

V1 mL

V2 mL

1mL

0

20

320

V3 mL

V4 mL

V5mL

0

50

30

2mL

2mL

0

2滴

20

10

已知:反应的方程式(未配平):KMnO4+H2C2O4+H2SO4→K2SO4+MnSO4+CO2↑+H2O

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答案(点此获取答案解析)

同类题1

阅读下面的文章,完成小题。

约定

孙道荣

    ①“咚,咚咚咚,咚咚——”他有节奏地轻敲着门。这是他和她约好的,这个敲门声就表示是他来了。

    ②门却没有立即打开。这可是少有的,以前,只要他轻轻地一敲门,门就打开了,好像她一直就等在门后似的。这一次,却没有动静。“咚,咚咚咚,咚咚——”他又有节奏地敲了一次。

    ③她是他的老客户了,差不多每隔五六天,她就会有一件快递,都是网上买的东西。他很惊讶,她都那么大岁数了,竟还是个网购达人。她家住四楼,按照快递的习惯,一般都是将包裹送到楼下,摁门铃或打电话,让货主自己下来取。第一次来送快递时,他摁响门铃,告诉她是送快递的,让她下楼来取。她慢腾腾地告诉他,自己岁数大了,上下楼不方便,能不能麻烦他送到楼上来。听声音,很苍老。他犹豫了一下,答应了。他“蹭蹭蹭”一口气爬上了楼,气喘吁吁地敲门。他很急,还有好多快递要送呢。她打开了门,一个白发苍苍的老太太签了单。看到他一脸汗水,她对他说,进来喝口凉水吧。他还真渴了,接过她递过来的水杯,他“咕咚咕咚”一口气喝干了。跑快递这么多年,这还是他第一次喝客人家的水。他谢她。老太太说,应该我谢你,以前别的快递员,都只送到楼下,只有你肯帮我送上楼。

    ④此后,每隔几天,就会有一个快递,只要送到老太太家的,他都是直接送上楼。老太太告诉他,自己一个人住,这个老小区,治安不是很好,不熟悉的人敲门,她是不开门的。所以,她和他约好了一个独特的敲门声,“咚,咚咚咚,咚咚——”她笑着说,有了这个暗号,就安全了。

    ④他和老太太很快就熟悉了。每次他送快递上楼,老太太都会让他进屋来坐一会,休息一下。他也实在是跑累了,正好休息调整一下。老太太为他倒好一杯水,温温的。他虽然进城打工好多年了,但除了偶尔和几个也是打工的老乡聚聚外,他很少和本地人打交道,每天,除了站在楼下喊“某某,快递到了”,他很少说话。他和老太太却能说上几句。他在送快递的路上,遇到了什么新鲜事,他都会讲给老太太听。无论他说什么,老太太都笑眯眯地听着,有时候,她也会讲讲自己年轻时的事情。他在这个城里,第一次感受到了家的温情。

    ⑦“咚,咚咚咚,咚咚——”他再次有节奏地敲门。他有点担心。是不是老太太病了?门打开了。是一个陌生的中年人。

    中年人说,是我母亲的,她前几天去世了,我代签吧。

    他怔住了。中年人请他进屋,说,我听母亲提起过你。他还没缓过神来。上次来送快递,老太太还很精神啊。

    ⑨中年人将他领进一个小房间,打开一个柜子,里面堆满了包裹,很多包裹,甚至都没有拆封过。他一眼就认出来了,那都是他亲手送过来的快递。中年人将刚刚签收的那件快递,也放进柜子里。转身对他说,这些东西,都是母亲从网上买来的,其实,她根本不需要这些东西。

    ⑩那、那她为什么买这些东西?他大惑不解。

    中年人摇摇头,我也不懂。还有一件奇怪的事,这些包裹上贴的快递单,后来都是你们快递公司的。没有任何别的一家快递公司,这说明,母亲在网购时,只选择由你们快递公司送达的店铺。

    中年人拍拍他的肩膀,哽咽地说,这些年,我光顾着在外打拼,未能尽孝,很少陪伴母亲一天,她连个说话的人都没有。兄弟,谢谢你!

他的眼眶也湿了。

同类题3

阅读下面的短文,掌握其大意,然后从短文后各题所给的A、B、C、D四个选项中,选择最佳选项。
                                                                Real Solutions(解决方法) to Problems

    Thirty engineers were working as a team in a company. They were young and eager to learn. The management decided to teach them about finding real solutions to problems

    One day, the team was called for a 1in a hall. They were quite surprised and all reached the hall holding various2. As they entered, they found a box placed in the center, full of flat balloons

    The manager asked everyone to pick a balloon and blow it up. Then they were asked to write their names on their respective(各自的)balloons 3so that the balloons wouldn't blow out. All tried, but not everyone was 4. Five balloons blew out due to pressure(压力).

    Those who failed to mark their names on the balloons were 5 out of the game. As a result, 25 engineers came to the next level. All the balloons carrying their names were 6 and then put into a room, here and there.

    The engineers were told to pick the balloon with his or her name on. All the 25 engineers began to search for the respective balloons in a rush. It was almost 15 minutes but no one was able to 7 the right one. The second level of the game was over.

    Then came the final level, the engineers were asked to pick any balloon and give it to person named on the balloon. Within a couple of minutes, all balloons 8 the hands of the respective engineers.

    The manager announced this was the real solution to the problem. Many times in our life, sharing and helping others give us real solutions to problems.