题干

下列不能达到实验目的是(   )

序号

实验内容

实验目的

A

用石墨电极电解Mg(NO3)2、Cu(NO3)2的混合液

比较确定铜和镁的金属活动性强弱

B

测同温同浓度Na2CO3和Na2SiO3水溶液的pH

确定碳和硅两元素非金属性强弱

C

室温下,用pH试纸测定浓度为0.1mol•L﹣1 NaClO溶液和0.1mol•L﹣1 CH3COONa溶液的pH

比较HClO和CH3COOH的酸性强弱

D

室温下,分别向2支试管中加入相同体积、相同浓度的Na2S2O3溶液,再分别加入相同体积不同浓度的稀硫酸

研究浓度对反应速率的影响

A:A  

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2015-02-10 05:15:35

答案(点此获取答案解析)

C

同类题4

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,并在答题卡上将该项涂黑。选项中有两项为多余选项。

        America's holiday shopping season started on Black Friday, the day after Thanksgiving.

____Shoppers make the most money this time of year, about 20 percent to 30 percent of all revenue all year. About 136 million people shopped during the Thanksgiving Holiday weekend.

____In an era of instant information, shoppers can use their mobile phones to find deals. Nearly 80 percent of this year's holiday shoppers, or about 183.8 million people, shopped on Cyber Monday.____Online spending on Black Friday rose 15 percent to hit $2.7 billion this year. Cyber Monday spending increased 12 percent to $3 billion. NBC News reported that for many, shopping online was a more comfortable alternative than crowded malls.

      The shift to online shopping has had a big impact on solid shopping malls. Since 2010, more than 24 shopping malls have closed and anadditional 60 are struggling. Fortune says the weakest of the malls have closed. However, the business in malls is thriving again, it adds.  According to a survey, 94.2percent of malls were full with shops by the end of 2014.____

      The average American consumer will spend about $805 on gifts. That's about $630.5 billion between November and December – an increase of 3.7percent from last year.

____That goes toChina's Singles' Day, celebrated on November 11, which posted record sales of$14.3 billion in 2015.

A.More and morepeople shop online nowadays.

B.That is thehighest level in 27 years.

C.It is thebusiest shopping day of the year.

D.One-in-fiveAmericans used a tablet or smart-phone.

E.Thetraditional mall industry can hardly survive.

F.Cyber Mondayfalls on the Monday after Thanksgiving and Black Friday.

G.Nonetheless,Cyber Monday is not the biggest online shopping day in the world.