Câu 7: B

Câu 8: D

em chụp gần hơn đc ko,chữ bé quá

Giúp em với ạ !!!! Câu 6 câu 7 câu 9 ạ !!!

Bài 7:

a: Ta có: \(A=4\sqrt{3+2\sqrt{2}}-\sqrt{57+40\sqrt{2}}\)

\(=4\sqrt{2}+4-4\sqrt{2}-5\)

=-1

Chụp thế này mà teo tức:(

7 Tim told me if I didn't have a degree, I couldn't get a job easily

8 I told Martin he could sleep well at night, if he didn't drink too much coffee

9 Jim told Daise unless she chooses the words more carefully, she would be introuble

10 I said to Dick I would forget Ann's birthday if he didn't remind me

11 Jim told Jane he wouldn't have been late for his intervire if he hadn't missed the train

12 I told my friends if it didn't rain that morning, we could go for a picnic

13 I said if Linda had been at home the day before, I could have visited her

14 They said if the weather were nice that day, they would go to the zoo

Câu 7 ạ mấy câu khác em tự biết làm

thế mà làm cho 1 tăng

Caai 7 :

a) C2H4 + Br2 $\to$ C2H4Br2

b) Theo PTHH : n C2H4 = n Br2 = 8/160 = 0,05(mol)

%V C2H4 = 0,05.22,4/2,24  .100% = 50%

%V CH4 = 100% -50% = 50%

Câu 8 :

a) C2H5OH = a(mol) => n CH3COOH  = 2a(mol)

$C_2H_5OH + Na \to C_2H_5OH + \dfrac{1}{2}H_2$
$CH_3COOH + Na \to CH_3COONa + \dfrac{1}{2}H_2$

Theo PTHH :

n H2 = 1/2 n C2H5OH + 1/2 n CH3COOH = 0,5a + a = 3,36/22,4 = 0,15

=> a = 0,1

=> m = 0,1.46 + 0,1.2.60 = 16,6(gam)

b)

$C_2H_5OH + CH_3COOH \buildrel{{H_2SO_4,t^o}}\over\rightleftharpoons CH_3COOC_2H_5 + H_2O$

Ta thấy : n C2H5OH < n CH3COOH nên hiệu suất tính theo số mol C2H5OH

n CH3COOC2H5 = n C2H5OH pư = 0,1.80% = 0,08(mol)

m este = 0,08.88 = 7,04(gam)

4 B

5 B

6 C

7 D

Exercise 2

1 of

2 about

3 juice

4 look

5 time 

6 get

Giúp em luôn câu8 với ạ 

4.B

5.B

6.C

7.B