1 A

2 C

3 A

4 D

5 C

6 B

7 B

8 A

9 B

10 D

Bài 5

\(n_{Al_2O_3}=\dfrac{10,2}{102}=0,1\left(mol\right)\)

\(n_{HCl}=\dfrac{18,25}{36,5}=0,5\left(mol\right)\)

PTHH: Al₂O₃ + 6HCl --> 2AlCl₃ + 3H₂O

Xét tỉ lệ: \(\dfrac{0,1}{1}>\dfrac{0,5}{6}\) => Al dư, HCl hết

PTHH: Al₂O₃ + 6HCl --> 2AlCl₃ + 3H₂O

            \(\dfrac{1}{12}\)<----0,5------->\(\dfrac{1}{6}\)----->0,25

=> \(\left\{{}\begin{matrix}m_{Al\left(dư\right)}=10,2-\dfrac{1}{12}.102=1,7\left(g\right)\\m_{AlCl_3}=\dfrac{1}{6}.133,5=22,25\left(g\right)\\m_{H_2}=0,25.18=4,5\left(g\right)\end{matrix}\right.\)

Bài 6

a) \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

\(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)

PTHH: Mg + 2HCl --> MgCl₂ + H₂

           0,1<-------------0,1<----0,1

=> \(n_{Mg\left(pư\right)}=0,1\left(mol\right)< 0,2\)

=> Mg dư => HCl hết

b) \(m_{MgCl_2}=0,1.95=9,5\left(g\right)\)

\(m_{Mg\left(dư\right)}=\left(0,2-0,1\right).24=2,4\left(g\right)\)

h tới mai mà k cs ng lm thì t lm hết h đi ngủ :>

1 stilt houses

2 speciality

3 diverse

4 unique

5 folk dances

6 costume

7 heritage site 

8 ornaments 

9 terraced fields 

10 ethnic minorities

`3)(x+4)/(x-3)-(x-3)/(x+4)=(x^2+18x+7)/(x^2+x-12)`

`đk:x ne 3,x ne -4`

Nhân 2 vế với `(x-3)(x+4) ne 0` ta có:

`(x+4)^2-(x-3)^2=x^2+18x+7`

`<=>x^2+8x+16-x^2+6x-9=x^2+18x+7`

`<=>14x+7=x^2+18x+7`

`<=>x^2+4x=0`

`<=>x(x+4)=0`

Vì `x ne -4=>x+4 ne 0`

`<=>x=0`

Vậy `S={0}`

23 D

24 C

25 A

26 C

27 D

28 C

29 B

30 B

31 C

32 C

33 B

34 C

35 C

36 C

37 D

38 C

39 C hoặc A (mk nghĩ là  A)

40 D

1 C

2 A

3 B

4 B

5 D

6 D

7 B

8 B

9 D

10 C

11 C

12 A

13 A

14 B

15 A

16 B

17 D

18 C

19 D

20 B

21 B

1 What does Micheal usually cycle in the central park for?

2 When did Hydro power became an electricity source?

3 How many free education prohrams have they organized?

4 Who won the Best Actor at the 88th Academy Awards?

5 Where are many people from the countryside moving to find work

Ex3

1 being young, she knows how to use water efficiently

2 Mary's sickness, she couldn't go to school

3 the bad weather, she went to school on time

4 studying hard, I passed the exam

5 the heavy rain, I couldn't go to school

Ex4

1 will be built for poor children next month

2 will be sold anywhere in my hometown

3 will be invented

4 to our village will be widened next year

5 will be used to go to school by students

1 There was an interesting documentary on television last night

2 Environmentally friendly vehicles are encouraged to develop

3 The festival starts with an opening parade through the streets where people walk

4 Solar energy is the cleanest and the most abudant source of energy

5  Overpopulation is one of the main reasons of air pollution

9 The last time I saw him was 8 days ago

10 It is Monday when I last took a bath

11 Samuel has kept a diary since 1997

12 We have learned English for 5 years

13 I have lived in HCM City since I was 8

14 She started teaching the children in this remote village for 5 months

15 The last time he wrote to me was in April