02.HảiAnh Bùi Lưu
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Khánh Đan
15 tháng 3 2023 lúc 21:33

Sửa đề: 4,46 (g) → 4,64 (g)

a, \(3Fe+2O_2\underrightarrow{t^o}Fe_3O_4\)

\(n_{Fe_3O_4}=\dfrac{4,64}{232}=0,02\left(mol\right)\)

Theo PT: \(n_{Fe}=3n_{Fe_3O_4}=0,06\left(mol\right)\Rightarrow m_{Fe}=0,06.56=3,36\left(g\right)\)

\(n_{O_2}=2n_{Fe_3O_4}=0,04\left(mol\right)\Rightarrow m_{O_2}=0,04.32=1,28\left(g\right)\)

b, \(2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\)

\(n_{KMnO_4}=2n_{O_2}=0,08\left(mol\right)\Rightarrow m_{KMnO_4}=0,08.158=12,64\left(g\right)\)

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Rosé
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_Sunn So Sad_
15 tháng 3 2023 lúc 21:23

Câu 6: Đọc đoạn văn, sau đó trả lời câu hỏi :

             My name is Nguyen Minh Trung. I’m a new student in class 6A. I’m from Da Nang and my family still lives there. In Ho Chi Minh City, I live with my grandparents at 21/3B Nguyen Trai street. My new school is not far from our house – about one kilometer, so I go to school by bike. There are a lot of students in my new school. But I don’t have any friends. I’m unhappy. I miss my parents, my sisters and my friends in Da nang.

56. Which grade is Trung in?..............................grade 6.....................................................................................

57. Is he a new student? yes, he is

58. Where is he from? he is from Da Nang

59. How far is it from his house to school? about 1 kilometer

60. What's his address? at 21/3B Nguyen Trai street

Câu 7.  Điền từ thích hợp vào chỗ trống:

          I have a  very close friend. Her name is Mai. She is eleven years old and she is in (61)......grade.................. six. She(62)..........can.............. speak English. She has English (63).........on.................Tuesday, Thursday and Friday. She can also (64)........play................. the piano. In her room,(65)...........there.................... is a piano and some books. Every day she gets up at six. She (66)........eats...................... breakfast at six thirty and goes to school at a (67)..........quarter.................... to seven. She has her (68)..........class...................... from seven o’clock to eleven thirty. Then she(69).........goes...................... home and has lunch at twelve o’clock. It’s three o’clock in the afternoon now and Nga is in her room. She (70)..........is.................doing her homework.

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Lê Minh Tuấn
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Hụnggjs
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Vy Thảo
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Tùng Chi Nguyễn
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Nguyễn Lê Phước Thịnh
15 tháng 3 2023 lúc 22:59

a: =>1/12*x^2=4/3

=>x^2=4/12*12=48/12=4

=>x=2 hoặc x=-2

b: =>1/5x-4/5=0 hoặc x+1/4=0

=>x=-1/4 hoặc x=4

c: =>5x+1/4=3/4 hoặc 5x+1/4=-3/4

=>5x=-1 hoặc 5x=1/2

=>x=1/10 hoặc x=-1/5

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Quyen Duong
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Nguyễn Lê Phước Thịnh
15 tháng 3 2023 lúc 23:08

 

Xét ΔEBD và ΔEAB có

góc EBD=góc EAB

góc E chung

=>ΔEBD đồng dạng vơi ΔEAB

=>EB/EA=ED/EB

=>EB^2=EA*ED

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