Câu 3: Nguyên tử X có số đơn vị điện tích hạt nhân là 25. Số lớp electron (có chứa electron) của X (ở trạng thái cơ bản) là:

         A. 5.                      B. 3.                                

       C. 2.                       D. 4.

Lập bảng biến thiên và vẽ đồ thị các hàm số sau:
a) y=x2 −3x+2 b) y=−x2 +4x−4 

c)y=2x2 −x       d)y=−x2 −2x+3

Giúp mình với :(

I.Complete the sentences with "Ving" and "to Vinf"

1.      He refused                    ( allow) her                     ( think) for herself.

2.      I was relieved                      (find out) that I had passed the exam.

3.       She made her son    _____(wash) the windows before he could go outside  _______(play) with his friends.

4.        She lets her children                (stay) up very late.

5.       We had nothing                 (do) except look at the cinema posters.

6.        We both heard him                (say) that he was leaving.

7.       It made him angry              (wait) for people who were late.

8.       I couldn’t understand what the passage said, so I had my friend                 ( translate) it for me.

9.      It’s important                 ( start) the meeting on time.

10.   There are too many people here for me               (talk) to all of them.

11.   Whenever I have free time, I like               ( watch) the basketball team                  (practice).

12.   She sent me an e- mail                 ( inform) me that the meeting had been canceled.

13.   I am happy                ( know) that you have passed the exam.

14.   We’ve got a few jobs                   ( do).

15.  He keeps (ask) ____________ me the time and I keep (tell) _____________him (buy) _____________himself a watch.

16.  I’m not in a hurry. I don’t mind (wait) _____________for you.

17.    I didn’t have enough time                  (finish) my work yesterday.

18.     He refused                    ( allow) her                     ( think) for herself.

19.  I was relieved                      (find out) that I had passed the exam.

20.  She made her son                   (wash) the windows before he could go outside              (play) withhis friends.

21.  She lets her children                (stay) up very late.

22.  We had nothing                 (do) except look at the cinema posters.

23.  We both heard him                (say) that he was leaving.

24.  It made him angry              (wait) for people who were late.

25.  I couldn’t understand what the passage siad, so I had my friend                 ( translate) it for me.

26.  It’s important                 ( start) the meeting on time.

27.  There are too many people here for me               (talk) to all of them.

28.   It took ages                (download) the pictures from the Internet.

29.  Whenever I have free time, I like               ( watch) the basketball team                  (practice).

30.  She sent me an e- mail                 ( inform) me that the meeting had been canceled.

31.  It was a thrill               ( see) my brother                   (win) the chess tournament last year.

32.  John helps me               ( choose) a present.

33.  I must                ( speak) to the manager.

34.  It’s cold. You had better                   ( wear) a coat.

35.  I’d rather                  ( stay) at home.

36.  My mother encourages me                  (learn) harder.

37.  She reminded him                ( close) the door carefully.

38.  My parents permit me                   ( go) camping with my classmates.

39.  She ordered him                     ( open) the door.

40.  I heard them                ( talk) in the next room.

41.  They let him                  ( write) a letter to his wife.

42.  I’ll lend you the book when I’ve finished (read) _____________it.

M là nguyên tố thuộc chu kì 4 và số electron lớp ngoài cùng của M là 1. M là:

            A. K                            B. Mg                        

  C. Ca                           D. Na

Các nguyên tố nhóm VIIA của bảng tuần hoàn, điều khẳng định nào sau đây là đúng?

           A. Các nguyên tố nhóm VIIA gọi là nhóm kim loại kiềm.     

           B. Dễ dàng cho 2e hóa trị lớp ngoài cùng.

           C. Dễ dàng cho 1e hóa trị để đạt cấu hình bền vững.                 

           D. Dễ dàng nhận thêm 1e để đạt cấu hình bền vững.

Cho các nguyên tố: X: 1s²2s²2p⁶3s², Y: 1s²2s², Z: 1s²2s²2p⁶3s²3p⁶3d¹4s², T: 1s²2s²2p⁶3s²3p⁵.Các nguyên tố thuộc cùng chu kì là:

A. X,Y            B. X,T                        

C. Y,Z             D. X,Z