题干

要除去以下四种物质中的少量杂质,所选用的除杂试剂不正确的是(  )

选项

待提纯的物质(括号内为杂质)

除杂试剂

A

NaOH(Na2SO4

Ba(OH)2溶液

B

KCl(CuCl2

KOH溶液

C

CO2(HCl)

NaOH溶液

D

Cu(CuO)

稀盐酸

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:2016-03-23 04:25:00

答案(点此获取答案解析)

C

同类题2

社会发展和环境保护日益成为全世界关注的问题。阅读材料,回答问题。

材料一

中国先秦时期己有许多关于环保的史料,《荀子·王制》中说“草木荣华滋硕之时。则斧斤不入山林。”……古代中国的环保工作由专职的“虞衡”部门负责。“虞”是山林川泽资源保护的监督机构,“衡”是山林川泽资源保护的执行机构。配合虞衡职司的还有一定的惩罚法令,如周文王时期曾颁布保护自然资源的《伐祟令》、《野禁》等。“有不如令者,死无赦。”……据《旧唐书》记载。当时政府还把京兆、河南两都四郊三百里划为禁伐区或禁猎区。北宋十分重视包括山场、林木、植被、河流、湖泊、鸟兽、鱼鳌等众多方面资源与环境保护方面的立法、执法。明清的法律则多沿用《唐律》。并有所发展。

——根据《古代环保制度之镜鉴》整理

材料二

英国是典型的“先污染,后治理”的国家……企业生产和利润的最大化成为支配企业的法则。如何解决生产越多环境污染越严重的难题,英国人在立法上对企业的社会责任进行规定,使企业成为环境保护的主体。议会的立法行动也促使了……政府从指导思想上由原来被动的自由放任转变为在法律的前提下积极主动地干预。……在英国环境治理过程中,起着重要作用的还有包括工人阶级在内的社会各个群体的不懈努力……使人们重新获得享有良好环境的权利。

——摘编自李宏图《英国工业革命时期的环境污染和治理》

同类题4

阅读理解

    A psychologist walked around a room while teaching stress management to the audience. As she raised a glass of water, everyone expected they'd be asked the “half empty or half full” question. Instead, with a smile on her face, she inquired. “How heavy is this glass of water?”

    Different answers are called out from the audience.

    She replied, “The absolute weight doesn't matter. It depends on how long I hold it. If I hold it for a minute, it's not a problem. If I hold it for an hour, I'll have an ache in my arm. If I hold it for a day, my arm will feel numb and paralyzed. In each case, the weight of the glass doesn't change, but the longer I hold it, the heavier it becomes.”

    She continued. “The stresses and worries in life are like that glass of water. Think about them for a while and nothing happen. Think about them a bit longer and they begin to hurt you. And if you think about them all day long, you will feel paralyzed and be incapable(无能力的)of doing anything.”

    It's important to remember to let go of your stresses. As early in the evening as you can, put all your burdens down. Don't carry them through the evening and into the night.

    Remember to put the glass down!”

    Comments:

    Aye Chan Aung-February 27, 2017 at 11:37am

    Short but valuable! It clearly teaches me how to deal with stresses.

    Nelson Malicdem-February 28, 2017 at 8:23 pm

    Wow! Thank the author and the one who submitted the article. I am experiencing a challenge when I read this. It gives me peace. What exactly is in the article is what I am doing. My burden actually paralyzes me without my knowing it. I put down the glass of water that I am holding. Thank you so much!