皮皮学，免费搜题
登录
搜题
【简答题】
实验室配制500mL 0.5mol?L -1 的NaCl溶液，有如下操作步骤： ①把称量好的NaCl晶体放入小烧杯中，加适量蒸馏水溶解； ②把①所得溶液小心转入500mL容量瓶中； ③继续向容量瓶中加蒸馏水至液面距离刻度l～2cm处，改用胶头滴管小心滴加适量的蒸馏水后停止滴加； ④用少量蒸馏水洗涤烧杯和玻璃棒2～3次，每次洗涤的液体都小心转入容量瓶，并轻轻摇匀； ⑤将容量瓶塞紧，充分摇匀． 请填写下列空白： （1）实验操作步骤的正确顺序为（填序号）______． （2）实验中用托盘天平称取NaCl晶体的质量是______． （3）上述操作步骤③中，如果加水超过了刻度线，处理？______． （4）若实验时出现如下情况，对所配溶液浓度将有何影响？（选填“偏高”、“偏低”、“无影响”） ①，俯视刻度线：______．②移液后，未洗涤烧杯和玻璃棒：______．
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】Would you mind______it to me once again?
A.
explaining
B.
to explain
C.
explain
D.
explained
【单选题】I explained on the phone that your request will be considered at the next meeting.
A.
I explained on the phone as your request will be considered at the next meeting.
B.
As I explained on the phone, your request will be considered at the next meeting.
C.
/
D.
/
【单选题】_________ I explained on the phone, your request will be considered at the next meeting.
A.
． When
B.
． After
C.
． As
D.
． Since
【单选题】The sentence wants ____ once more.
A.
explaining
B.
to explain
C.
being explained
D.
explained
【单选题】I explained on the phone that your request will be considered at the next meeting.
A.
I explained on the phone as your request will be considered at the next meeting.
B.
As I explained on the phone, your request will be considered at the next meeting.
【单选题】In general， the old man is generous. But ____， he was mean to an old beggar. A．at once B．once aga
A.
22.In general， the old man is generous. But ____， he was mean to an old beggar. A．at once
B.
once again
C.
for once
D.
once over
相关题目：