Người ta điều chế phân đạm urê từ đá vôi,không khí, nước, chất xúc tác theo sơ đồ chuyển đổi sau :

H₂O điện phân→H₂ (1)

không khí  hoalong→N₂(2)         (1)+(2)→NH₃

CaCO_{3  to}→CO_{2    NH3}→CO(NH₂)₂

_a)Viết các PTHH trong sơ đồ chuyển đổi trên_.

_b)Muốn điều chế được 6 tấn urê  cần phải dùng bao nhiêu tấn NH₃ và CO₂?m³  khí NH₃ và CO_{2 ở đktc?}

GIÚP MÌNH VỚI Ạ

Cho tam giác ABC,có A=90 độ+góc B, đường cao CH.Chứng minh:

a)góc CBA=góc ACH

b)CH^2=BH.AH

Cho tam giác ABC có các đường cao BD và CE cắt nhau tại H.

Chứng minh: Tam giác EHD đồng dạng với tam giác HBC

Finish each of the sentences in such a way that it stays the same as the sentence printed before it.

37. David said, “I cannot read your writing.”

→ David said 

38. Mary asked, “Will we still have traffic jams in 30 years’ time?”

→ Mary asked ……………………………………………………………………………………………

39. He spends three hours a day doing the homework.

→ It takes

40. Because the weather was bad, he stayed at home.

→ Because of

Use the words / phrases given to make meaningful and correct sentences. You can add some more words or make some changes.

33 We/ use/ music/ communicate/ year/ 2100

34. They said/ there/ be/ water/ Mars.

35. They / ask/ what food/ people/ other planets/ eat.

36. Mary / enjoy/ chat/ the phone/ her friends.

Read the following passages and circle the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.

The Mary Celeste was built in 1861 in Canada. When it was launched .It was given the name The Amazon. It was not a lucky ship. The first captain died a few days after it was registered and on its first voyage in 1862 it was badly damaged in a collision. When it was repaired in port, it caught fire. In 1863 it crossed the Atlantic for the first time, and collided with another ship in English Channel. Four years later, in 1867, it ran around on Cape Breton Island off the Canadian coast. The ship was almost completely wrecked and had to be rebuild. It was then sold and the name was changed to the Mary Celeste.

29. Where and when was the Mary Celeste built?

A. in Canada in 1861              B. in Canada in 1862  C. in Canada in 1863              D. in Canada in 1867

30. What was its first name?

A. The Mary Celest                B. The English ship    C. The Amazon                       D. The Atlantic

31. What happened to the ship when it was repaired in port?

A. It broke                                                                   B. It caught fire          

C. It collided with another ship                                  D. It sunk

32. How many times did it collide with other ship?

A. once                                    B. three times             C. four times                           D. twice