Hợp chất X có công thức phân tử là  C 2 H 7 O 3 N . X tác dụng với dung dịch NaOH và HCl đều giải phóng khí. Khi cho m gam X tác dụng với dung dịch HCl dư rồi hấp thụ hoàn toàn khí thu được vào dung dịch  Ca OH 2  dư, thu được 10,0 gam kết tủa. Giá trị của m là

A. 9,5.

B. 9,4.

C. 9,1.

D. 9,3.

lặn vài tháng *ngoi lên*

Trên web hoc24h này cũng có nè, mấy khóa học của @Lê Nguyên Hạo rồi @Đức Minh

"Emails are better than letters" - I think it's true. Because once you send an email, the time before the recipient gets it is typically less than a second. On the other hand, letters can take days or, in extreme cases, weeks to reach their destination. For more, Paper, on the other hand, can be burned, shredded, lost or otherwise destroyed. Otherwise, emails, can be rich in multimedia. You can add music, spoken words or other sound effects. Letters are static, but emails can be jumping-off points for more information. And Email is a lot less work. Finally, Use secure email and encryption programs for very sensitive material and it's virtually impossible for anyone to read your email.

That's my own idea.

1.''tom and jerry''is a walt disney....cartoon......

2. A ..contestant....is a person who takes part in a contest.

3.They are ......perfoming......a history play tonight.

4.The....audience....applauded the performance for five minutes.

5.Oliver twist is a.....character......in the novel of Charles Dickens.

(Quyển tiểu thuyết này mình đọc rồi, hâm mộ Charles Dicken kinh khủng)

6. TV .....viewers.....can join answering questions through telephone or by mail.

7.Picasso was a great Italian...artist..........

My teacher always drives very carefully.

=> How carefully in driving my teacher always does !