Mô tả sự hình thành liên kết lon trong các hợp chất sau: NaCl, CaCl2, Na2O, K2S, MgCl2, MgO, CaO, Al2O3.

3. Tìm nguyên tử khối trung bình của nguyên tử a. Bo có 2 đồng vị: 5 ^ 10 B(18 %); 5 ^ 11 B(81,11\%) . b. Kẽm có 3 đồng vị: 30 ^ 64 Zn(50,3\%) 30 ^ 66 Zn(31,1\%) ; 30 ^ 68 Zn(18,6\%) c. Magie có 3 đồng vị: 12 ^ 24 Mg(78,6\%) ; 12 ^ 25 Mg(10\%): 12 ^ 26 Mg(11,4\%) .

1. My father seldom (watch).. 2. Hoa always (learn). ....romantic films. .....her lessons at 7pm 3. What time........... your English class (begin)........ 4. Water (boil). (freeze)........ At 100 Celsius degree and .......at zero degree. 5. John (buy)......... 6. In the past people (travel).. a new mobile phone a few days ago. by horse. 7. When my father (be) .......... very well. ....young, he (play) ...football 8. ….... you * (go) ....…..... to Mary's party last Saturday? 9. People (not use)...............typewriters any more. They (type)............ everything on computer. 10. John (work)............ for a humanitarian international organization. He (travel) around the world to help the poor women and children 11. Terrorists ( ck)........... the Twin Towers in September 11^ \$ , 2001 12. Peter (not attend).. the meeting last Tuesday because he (forget)...it 13. We (not watch)....... ...... the match last night because we (go).............to the cinema 14. When .........you (graduate).. from university? - in 2008 15. Yesterday Tung (use his cell phone in the Maths lesson, so he (be)..... punished by the teacher. 16. Who (teach).......... ..you last semester.

WRITE A SHORT PARAGRAPH ABOUT A FARMER'S DAILY ROUTINE (AROUND 100 WORDS)

Câu 4: Xác định nồng độ phần trăm của dung dịch thu được khi cho 14 gam KOH vào 160ml nước (d = 1g / m * l) .