题干

配制100mL0.20mol/L KCl溶液时,某学生用托盘天平将准确称量的1.49gKCl固体放入烧杯中,加入约40mL蒸馏水,用玻璃棒搅拌使其溶解.将溶液由烧杯倒入100mL容量瓶中,然后往容量瓶中小心地加入蒸馏水,直至液面接近刻度2cm~3cm处.改用胶头滴管加蒸馏水,使液面达到刻度线.把容量瓶盖紧再振荡摇匀该生操作中的错误是____________
上一题 下一题 0.0难度 选择题 更新时间:2017-07-14 08:01:48

答案(点此获取答案解析)

托盘天平精确值为0.1g,不能称量1.49g固体,移液前没进行冷却,移液时没用玻璃棒引流

同类题4

任务型阅读

    Unless you think you're the smartest, who doesn't want to be smarter? Of course I want to be smarter too. So I try to find out who's the real smart guy that maybe I can learn from.____

    They probably do social media. Not always, but probably.____They also use this to ensure they can feed their brains with things they otherwise wouldn't have come across.

    ____ They never bother their head about the problem of "work-life balance" and somehow manage to seem 100% engaged in what they're doing, on all fronts simultaneously(同时),even though you know they're taking appropriate steps behind the scenes to make sure their lives are well balanced.

    They know they are the smartest in the room, but they don't spend much time talking about that.____ That is, they challenge themselves to make everyone else in the room the smartest person too.

    They never, ever, under any circumstances, make you look stupid, even though it would be easy to do so. They've learned through bitter experience that the only thing that happens when you make someone look bad is that you look bad yourself.

    If they are managers, they will make every effort to get people more connected and more popular than them in their teams.____They're not threatened because they know that smartness is synergistic.(相互促进的).

A. It is not only a chance to listen.

B. They know it is an advantage to them.

C. They take it as a personal challenge instead.

D. They will be smiling even when things go wrong.

E. Now I've got an answer about whether someone's smart.

F. They also ensure their smart people look smarter than them.

G. They deal with home, work and personal interests perfectly.