题干

a、b 两种物质的溶解度曲线如图所示.下列说法不正确的是(  )

A:15℃时,a、b 的溶解度均为20g

B:加水或升温均可使b的饱和溶液变为不饱和溶液

C:将 30℃时a的饱和溶液降温至15℃,溶质的质量分数不变

D:20℃时分别向100g 水中加入20ga和 b,升温至30℃,所得溶液均为饱和溶液

上一题 下一题 0.0难度 选择题 更新时间:2017-03-06 03:04:37

答案(点此获取答案解析)

D

同类题1

阅读下列文字,回答文后问题:
        “什么是爱情?……在上帝创造世界时,他就把一切生物分散安置在地土并且教会他们传宗接代,繁衍自己的子孙。给男人和女人都分了土地,教给他们如何筑造窝棚,又给男人一把铲子,女人一把谷粒。‘生活下去,繁衍你们的后代吧。’上帝对他们说道,‘我去忙自己的事了。一年以后我再来,看看你们这里的情形。’
        “刚过一年,上帝带着大天使加夫里拉就来了。那正是清晨,太阳升起的时候。他看到,窝棚旁坐着一个男人和一个女人。他们面前的田地里是一片成熟的谷物。而在他们旁边放着一只摇篮,摇篮里躺着个熟睡的婴儿。那男人和女人一会儿望望天空,一会儿你看看我,我看看你,相互传情。在他们目光接触的刹那间,上帝从那目光中发现了一种他所不理解的美和某种从未见过的力量。这种美胜过天空和太阳、大地和麦田──胜过上帝所创造的一切。这种美使上帝迷惑不解,惊慌不已。
        “‘这是什么呀?’他向大天使加夫里拉问道。
        “‘这是爱情。’
        “‘爱情是什么意思?’
        “大天使无可奈何地耸耸肩。上帝走到男人和女人面前追问他们,什么是爱情。可是,他们也无法向他解释。于是上帝勃然大怒。
        “‘好呀!看我不惩罚你们才怪!从现在起你们就要变老。一生中的每时每刻都将消磨你们的青春和力量直到化为乌有!五十年后我再来,看看你们眼睛里还留存着什么东西,该死的人……’”
       “上帝为什么要发怒呢?”我问了奶奶一句。
        “是因为没有经过请示就创造了一种他自己闻所未闻、见所未见的东西。你还是往下听吧!五十年后上帝同大天使加夫里拉又来了。这次他看到,原来有窝棚的地方已盖起一幢圆木造的房子,荒地变成了果园,地里一片金黄色的麦穗,几个儿子在耕地,女儿在收麦子,孙子们在草地上嬉戏。老头儿和老太婆坐在屋前,时而望望红艳艳的朝霞,时而你看看我,我看看你,相互传情。上帝在这对男女的眼睛中看到了无与伦比的美和更大的力量,其中还含有一种新的东西。
       “‘这是什么?’他问大天使。
        “‘忠诚。’大天使答道,但还是解释不清楚。
        上帝怒不可遏。
       “‘你老得还不够快吗,该死的人?你活不多久了。我还要来,看看你的爱情还能变成什么样!’
       “三年以后,上帝带着大天使加夫里拉又来到这里。一看,有个男人坐在小土丘上。他的一双眼睛充满忧郁悲伤的神情,但目光中却仍然使人感到一种不可理解的美和那种同过去一样的力量。这已经不仅仅是爱情和忠诚了,还含有别的东西。
       “‘这又是什么?’他问大天使。
       “‘心灵的追念。’
       “上帝手抚胡须,离开了小土丘上的老头儿。举目向麦田、向火红色的曙光望去:金黄色的麦穗中站着许多青年男女,他们一会儿望望火红的天空,一会儿你看看我,我看看你,相互传情……上帝久久地伫立凝视着。随后深沉地思索着离去了。从那时起人就成了大地上的上帝。
       “这就是爱情,小孙子。爱情,它高于上帝。这是人类永恒的美和力量。人们世代交替,我们每个人都不免变成一抔黄土,但爱情却成为人类种族的生命力永不衰败的纽带。”
         这就是爱情,亲爱的女儿。万物生存、繁殖、传宗接代,但只有人才能够爱。同样,从人本身来说,只有能以人的方式去爱的人,才成为真正的人。如果不善待爱情,便不能提高到人类美这一高度,就是说它还仅仅是能够成为人、但尚未成为真正的人的一种生物罢了。

同类题2

根据短文理解,选择正确答案。

    Newborns begin to develop language skills long before they begin speaking. And, compared to adults, they develop these skills more quickly. People have a hard time learning new languages as they grow older, but babies have the ability to learn any language easily.

    For a long time, scientists have tried to explain how such young children can learn the complicated grammatical rules and sounds of a language. Now, researchers are getting a better idea of what's happening in the brains of the tiniest language learners. This new information might help kids with learning problems as well as adults who want to learn new languages. It might even help scientists who are trying to design computers that can communicate like people do.

    Most babies go “ma ma” by 6 months of age, and most children speak in full sentences by age 3. For many years, scientists have wondered how the brains of young children figure out how to communicate using language. With help from new technologies, scientists are now finding that babies begin life with the ability to learn any language. They get into contact with other people, listen to what they say and watch their movements very closely. That is why they quickly master the languages they hear most often.

    Studies show that, up to about 6 months of age, babies can recognize all the sounds that make up all the languages in the world. Starting at around 6 months old a baby's brain focuses on the most common sounds it hears. Then, children begin responding only to the sounds of the language they hear the most.

    In a similar way older babies start recognizing the patterns that make up the rules of their native language. For example, English children who are about 18 months old start to figure out that words ending in “-ing” or “-ed” are usually verbs, and that verbs are action words.