cau 6 sai roi ban

Câu 2:D

Câu 3:D

Câu 4C

Câu 5B

Câu 6D

Câu 4 : Tham khảo : 

Câu 4:

Câu 3 : 

A : H2S

B: FeCl3

C: S

F: HCl

G: Hg(NO3)2

H: H2S

I: Hg

X: Cl2

Y : H2SO4

PTHH:

H2S + 2FeCl3 ⟶ 2FeCl2 + 2HCl + S (kết tủa màu vàng)

Cl2 + H2S ⟶ 2HCl + S (kết tủa màu đen)

4Cl2 + 4H2O + H2S ⟶ H2SO4 + 8HCl

BaCl2 + H2SO4 ⟶ 2HCl + BaSO4 (kết tủa trắng )

Hg(NO3)2 + H2S → 2HNO3 + HgS ( kết tủa đen)

HgS + O2 ---^_to→ Hg (màu trắng bạc)  + SO2

1. While I was staying in Paris last summer, I met her.

2. When we were having dinner, there was a knock at the door.

3. When did you start studying English.

4. He used to visit me on Sundays when he studied in England.

5. Saving some pocket money for charity work is meaningful.

6. Our children find it interesting to give away their old books to needy people.

7. It's a year since we last saw Mary.

a, 25/12

b,  25/72

a) = 3/4 + 4/3 = 25/12

b) = 3/8 - 16/9 = -101/72 * hình như hơi sai sai:"> *

Diện tích tam giác nhân 2 rồi chia đáy tương ứng

S x 2 : đáy