Bài 1: \(n_{CuO}=\dfrac{3,2}{80}=0,04\left(mol\right)\)

\(CuO+H_2SO_4\rightarrow CuSO_4+H_2O\)

0,04  →  0,04

\(\Rightarrow m_{H_2SO_4}=0,04\cdot98=3,92\left(g\right)\)

\(\Rightarrow C\%_{H_2SO_4}=\dfrac{3,92}{80}\cdot100\%=4,9\%\)

Bài 2: \(n_{HCl}=0,2\cdot2=0,4\left(mol\right)\)

\(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2\uparrow\)

\(\dfrac{1}{15}\)     ←    0,4

\(\Rightarrow m_{Fe_2O_3}=\dfrac{1}{15}\cdot160=\dfrac{32}{3}\left(g\right)\)

dài thế bn, tách ra đi

Tham khảo

1. She bought this shirt yesterday

this shirt was bought yesterday

2. This baby drinks milk every day

milk is drunk by This baby every day

3. The students have cleaned the room

the room has been cleaned by The students

4. I can do these exercise

these exercise can be done by me

5. The students are writing the lessons now

the lessons are being written by The students now

6. we shall visit him tomorrow

He shall be visited tomorrow

7. he has his wife wash the clothes

he has the clothes washed by his wife

8. The students have done the test

the test has been done by The students

9. she is writing the letter now

the letter is being written now

10. he had decorated the house before last Tet

the house had been decorated before last Tet

11. we eat rice every day

rice is eaten every day

12. they were watching a film at the time

a film was being watched at the time

13. the children are singing a song now

a song is being sung by the children now

14. we have learnt thí unit

This unit has been learnt

15. he sent him a letter yesterday

A letter was sent to him yesterday

16. thay planted the trees in the garden

The trees were planted in the garden

17. he drank all the water in the bottle

all the water in the bottle was drunk

18. i will do that work for her

that work will be done for her

19. we have our mother wash the clothes

we have the clothes washed by our mother

20. Lan has got her bike repaired by Ba

1 this shirt was bought yesterday by her

2,Milk is drunk everyday by this baby

3,The room has been cleaned by the students

4,These exercise can be done by me

5,The lessons are being written now by the students

6,He will be visited tomorrow by us

7He has His wife washed the clothes

8,The test has been done by the students

9,The letter is being written now by her

10,The house has been decorated by him

11Rice is eaten everyday by us

12,A film was being watched by us at that time

13, The show is being sung by the children now

14,This unit has been learnt by us

15,He is sent a letter yesterday by him

16,The trees were planted in the garden by thêm

17,All the water in the bottle was drunk by him

8,That work will be done for her by us

19,We have the clothes washed by our mother

20,Lan has got her bike repaired by Ba

a: Xét ΔABM và ΔDBM có

BA=BD

\(\widehat{ABM}=\widehat{DBM}\)

BM chung

Do đó: ΔABM=ΔDBM

b: Ta có: ΔABM=ΔDBM

nên \(\widehat{BAM}=\widehat{BDM}=90^0\)

c: Ta có: BA=BD

nên ΔBAD cân tại B

mà BM là đường phân giác

nên BM là đường cao

d: Ta có: ΔABM=ΔDBM

nên MA=MD

Ta có: BA=BD

nên B nằm trên đường trung trực của AD(1)

Ta có: MA=MD

nên M nằm trên đường trung trực của AD(2)

Từ (1) và (2) suy ra BM là đường trung trực của AD

hay BM⊥AD