- Trích từng mẫu thử và đánh dấu.

- Nhúng quỳ tím lần lượt vào các lọ mất nhãn đó, ta được:

+ Quỳ tím hóa đỏ --> H₂SO₄

+ Quỳ tím hóa xanh --> Ba(OH)₂

+ Quỳ tím không chuyển màu --> NaCl ; H₂O

- Dùng thuốc khử AgNO₃ vào 2 dd không chuyển màu trên, ta được:
+ Chất nào có kết tủa trắng là NaCl

NaCl + AgNO3 --> NaNO3 + AgCl\(\downarrow\)

+ Không hiện tượng là H₂O

- Cách phân biệt: dùng thuốc khử Na₂CO₃

+ Chất nào có kết tủa trắng là CaCl₂

PTHH: CaCl₂ + Na₂CO₃ --> CaCO₃\(\downarrow\) + 2NaCl

+ Không hiện tượng là NaCl

1. Letters are typed in the office by Mary.

2. You will be helped by his father tomorrow.

3. The human life has been completely changed by science and technology.

4. This bottle was broken by Peter.

5. English is being learnt/ learned in the room.

6. My mind can’t be changed.

7. I hadn’t been told about it.

8. Her telephone number isn’t known.

9. The children will be brought home by my students.

10. I was sent a present last week.

11. We were given more information.

12. All the workers of the plan were being instructed by the chief engineer.

13. Tea can’t be made with cold water.

14. Some of my books have been taken away.

15. The meeting will be held before May Day.

16. The engine of the car has to be repaired.

17. The window was broken and some pictures were taken away by the boys.

18. A lot of money is spent on advertising every day.

19. A story is going to be told by teacher.

20. A cake is being cut with a sharp knife by Mary.

21. The woman with a red hat was looked at by the children.

22. The victims have been provided with food and clothing.

23. English is spoken in almost every corner of the world.

24. This machine mustn’t be used after 5:30 p.m.

25. After class, the chalk board is always erased by one of the students.

1. They grow rice in tropical countries.

→ rice ____is grown in tropical countries_____

2. Mr. Green loves his children very much.

→ his children ___are loved very much by Mr.Green___

3. People don’t speak French here.

→ French ___isn't spoken here___

4. Someone broke his windows last night.

→ his windows __were broken last night__

5. Children should treat old men with respect.

→ old men __should be treated with respect by children__

6. The computer can do all the accounts.

→ all the accounts __can be done by the computer__

7. They are going to build a new school.

→ a new school __is going to be built___

8. He isn’t going to buy that house.

→ that house __isn't going to be bought__

9. They will pull down that building

→ that building __will be pulled down__

10. They will pull down that building

→ That building ___will be pulled down___

11. The teacher won’t correct the exercises tomorrow.

→ The exercises __won't be corrected by teacher tomorrow__

12. The teacher will give her a prize .

→ She__will be given a prize by the teacher__

13. Her mother bought her a doll last week.

→She__was bought a dool by her mother last week__

14. Jack has typed the article recently.

→ the article ___has been typed by Jack recently___

15.Teacher make the students do a lot of homework.

 →Students__are make to do a lot of homework by teacher__

1.Lan is tired (now) because she watched TV late last night

2.If people fly less, the air will be less polluted

Khi hai mảnh ni lông được cọ xát với nhau thì hai mảnh ni lông nhiễm điện và sẽ hút lại với nhau

Đốt cháy hoàn toàn hợp chất hữu cơ A chứa C và H thu được 17,6g CO2 và 10,8g H2O a)Tính khối lượng của hợp chất A đã dùng b)Tính khối lượng của khí O2 cần để đốt hết lượng A

Có ai muốn làm bạn trai mình ko?? Ai đồng ý mình cho thấy mặt.

??