题干

有Al、CuO、Fe2O3组成的混合物共10.0 g,放入500 mL某浓度的盐酸中,混合物完全溶解,当再加入250 mL2.00 mol/L的NaOH溶液时,得到沉淀最多。上述盐酸的浓度为(   )

A:1.00 mol/L

B:0.500 mol/L

C:2.00 mol/L

D:3.00 mol/L

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答案(点此获取答案解析)

A

同类题3

根据短文理解,选择正确答案。

    Having experienced a shocking electrical accident, which caused him to become both blind and deaf, James Franco's world became completely dark and quiet for almost ten years. The loss of sight and hearing threw him into such sorrow that he tried a few times to put an end to his life. His family, especially his wife, did their best to tend and comfort him and finally he regained the will to live.

    One hot summer afternoon, he was taking a walk with a stick near his house when a thunderstorm started all at once. He stood under a large tree to avoid getting wet, but he was struck by lightning. Witnesses (目击者) thought he was dead but he woke up 20 minutes later, lying face down in muddy water. He was trembling badly, but when he opened his eyes, he could hardly believe what he saw: a tree and a muddy road. When Mrs. Franco came running up to him, shouting to their neighbors to call for help, he could see her and hear her voice for the first time in nearly ten years.

    The news of James regaining his sight and hearing quickly spread and many doctors came to examine him. Most of them said that he regained his sight and hearing from the shock he got from lightning. However, none of them could give a compelling answer as to why this should happen. The only reasonable explanation given by one doctor was that, since James lost his sight and hearing as a result of a sudden shock, perhaps, the only way for him to regain them was by another sudden shock.

同类题5

阅读下文,回答问题

       已经客满的大巴车打了个饱嗝儿,停了一下,又上来两个青年男人,一个甩着手,一个夹着公文包。“公文包”的脚后跟还在车门外边,客车就又开动了。

       甩手青年坐在门口的马扎上,“公文包”顺手将公文包放在行李架上就直奔车后座去了,那样子好像他买了对号入座的票,最后一排正有一个空位子热情地等着他的屁股呢。事实上他奔的不是座位,而是座位上的人,最后排靠左的那个胖男人正在熟睡中,“公文包”的手灵巧地伸进胖男人的上衣衣兜里,夹出一把单据名片之类的东西,显然这类东西不是“公文包”想要的,就又放回原处,然后揪住了胖男人的衣领,甩给他左右两个嘴巴。

       胖男人抹了一把脸,把拳头捏得咯咯响,只一下就反剪了“公文包”鸡爪子一样的手,然后拨打110,将贼人绳之以法。

       事实上没有,胖男人只是活动活动肩膀,整理一下衣服,继续睡去了,发生了什么全当梦一场。

       “公文包”又瞄准了一个打瞌睡的小伙子,小伙子的手机在牛仔裤的裤兜里,清楚地凸现着它的形状,“公文包”细长的手指在这个形状外游弋了一阵子,牛仔裤绷得太紧,硬拽怕是要惊醒梦中人了。

       原来这个小伙子在假寐,他一把就抓住“公文包”的手,像扔抹布一样地将他扔出车外。

       事实上没有,小伙子的确在假装睡觉,他也抓住了“公文包”那只游弋的手,不过他悄悄地给放了。“公文包”感觉到这只手的力量,小伙子真跟自己斗等于缚鸡。对这样的主儿还是离远一点。

       这时他的目光落在一个女式皮包上,皮包被抱在女孩的怀里,由于女孩也在打瞌睡,抱包的胳膊有些松弛,但拉链的开端在女孩的胳膊下压着。“公文包”变戏法儿似的手里多出一个贼亮亮的刀片!他用食指和中指夹着,修长而白皙的手指看上去那么优美。

       “叔叔,你的手真好。”

       女孩旁边一个七八岁的男孩打破了车里黑夜一般的寂静。自从这两个人上车,大胡子司机和女售票员的说笑就戛然而止,女售票员将马扎腾给甩手青年,自己坐在大胡子身后一个袋子上,将肥硕的屁股伸给所有的乘客,然后一丝不苟盯着前方,天塌地陷与她无关了。

       “叔叔,”男孩又开始说话了,“你的手指这么长,钢琴一定弹得很棒,老师一定很喜欢你,老师也喜欢我,只是我的手还小,够不到八度。”

       男孩的一番话使那个贼亮亮的刀片离开了女孩的包,被握在有着细长手指的手里。手的主人随着车身的颠簸,身子斜歪了一下。那个甩手青年递过来一只马扎。“公文包”坐下。额头上亮亮的,是汗。

       “叔叔,我才考钢琴二级,我要是有你这么长的手就可以多考,至少四级,叔叔,今天你也去考试吗?考几级啊?”

       “公文包”看了一眼男孩,男孩也看着他,期待着他的回答。

       “叔叔的确弹过钢琴,‘六一’的时候还上台演出过,这双手曾将钢琴七级的曲子弹得流水一般,不过那是十三年以前的事情。我的钢琴老师说我是他教的学生当中资质最好的,手指上的天分最高。父母也希望我将来是最优秀的钢琴演奏家。可是后来父母离婚了。虽然他们争着要我,可是我谁也不跟,我离家出走,流浪街头,就被一个团伙看上了这双手。从此这双手在滚烫的肥皂水里接受另外一种训练。(A)看见门口那个人了吗,看见大胡子了吗,看见大屁股了吗,就是司机和卖票的,都是一伙的。我只是干活,等着分成的人不止这仨呢。小弟弟,这双手如果不给他们干活,回去就得少一截指头,这辈子就别想弹琴了。”

       “公文包”想用手去抚摸一下男孩的头,告诉他这一切。

       事实上他没有。他只是将那双手攥紧了,躲开男孩期待的目光①,也回避门口那人刀剜一样的目光②,他知道自己已经被乘客的目光③包围。

       (B)男孩等不到回答就只好盯着那双手,盯着盯着,就见一只红色的小虫子从指缝里探头探脑地钻出来,接着第二只,第三只。

       “叔叔,”男孩说,“你的手,流血了。”

       “公文包”用另一只没有流血的手轻轻抚摸了一下男孩的头,在大巴车再次打了饱嗝儿停下的时候,“公文包”夹着他的公文包和甩手青年就下车了。