题干

 A、B两种固体物质的溶解度曲线如图所示,请根据曲线图回答下列问题.

(1)现有常温下B的不饱和溶液,在只要求保持其中溶剂质量不变的条件下,将其变成饱和溶液,可行的方法有____.

(2)现有一杯t1℃时含A、B两种物质且均饱和的混合溶液,若要从中分离出少量A的纯净物,其操作方法是____.

(3)下列说法正确的是____ .

①t2℃时,A的溶液中溶质的质量分数一定比B的溶液中溶质的质量分数大;

②将t2℃A、B的饱和溶液分别降温至t1℃,此时两溶液中的质量分数相等;

③在t1℃时,用两份等量的水分别配制成A、B的饱和溶液,这两种溶液的质量相等;

④在t2℃时,用等量的A、B分别配制成两种饱和溶液,测得其质量依次为m1g和m2g,则m1<m2.

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加入溶质,降温结晶,③④

同类题1

阅读下列短文,从每题所给的A、B、C和D四个选项中,选出最佳选项。

    At least 40% of Australian households now have at least one home “Internet of Things” device. These are fridges, window blinds, locks and other devices that are connected to the Internet.

    While the Internet of Things (IoT) may lead to more efficiency in our daily lives, my research shows that consumers are exposed to many risks by the use of IoT devices, ranging from disclosure of private information, to physical injury and problems with the devices themselves.

    Australia has no specific laws aimed at addressing IoT issues, and current laws intended to protect consumers have gaps and uncertainties when dealing with IoT devices. Many IoT device manufacturers and suppliers show little regard for customers' privacy. Some even make money from customer data.

    Consumer electronics company Vizio recently agreed to pay US regulators US $ 2.2 million, after failing to get appropriate permission from users to track their TV viewing habits.

    Late last year, the Norwegian Consumer Council found that a children's doll recorded anything said to it by children and sent the recordings to a US company. The company reserved the right to share and use the data for a broad range of purposes.

    IoT devices have the potential to collect more private data about individuals than was possible with previous devices. All this data can then be used to study consumers, predict our behavior, and sell us products at times when our willpower is lowest. Some companies are currently using technology to track consumers through stores and send their messages to mobile phones. This may be linked to our purchase history.

    Consumers are exposed to significant risks from IoT devices, from the use of data, to security flaws and devices no longer being supported. They should think long and hard about the risks they are taking on with IoT devices. Do you really need that internet-connected hairbrush?