Những câu hỏi liên quan
TT
Xem chi tiết
PU
24 tháng 5 2021 lúc 11:25

III. 

A. 

1. B

2. C

3. B

4. A

5. D

B. 

1. C

2. B

3. B

4. A

5. C

Bình luận (0)
MN
18 tháng 11 2021 lúc 20:30

1 b c b a d

2 c b b a c nha

Bình luận (0)
 Khách vãng lai đã xóa
TT
Xem chi tiết
DH
24 tháng 5 2021 lúc 11:14

1 The meeting was canceled 3 days ago

2 She told me she was watching a film with her sister then

3 I admire the guitarist who is perfroming on the stage

4 Had it not been for Pauline's interest, the project would have been abandoned 

Bình luận (0)
PU
24 tháng 5 2021 lúc 11:20

IV. 

1. The meeting was canceled 3 days ago.

2. She told me shewas watching a film with her sister then

3. I admire the guitarist who is performing on the stage

4. Had it not been for Pauline's interest, the project was abandoned. (chắc thế)

Bình luận (0)
H24
Xem chi tiết
NT
19 tháng 12 2021 lúc 14:53

b: Để hai đường thẳng song song thì m-4=1

hay m=5

Bình luận (0)
NM
19 tháng 12 2021 lúc 14:58

\(b,\Leftrightarrow\left\{{}\begin{matrix}m-4=1\\m-1\ne3\end{matrix}\right.\Leftrightarrow m=5\\ c,\Leftrightarrow A\left(3;0\right)\in\left(d_2\right)\Leftrightarrow3m-12+m-1=0\Leftrightarrow m=\dfrac{13}{4}\\ d,\text{PT giao Ox và Oy: }\left\{{}\begin{matrix}y=0\Leftrightarrow x=\dfrac{1-m}{m-4}\Leftrightarrow OA=\left|\dfrac{m-1}{m-4}\right|\\x=0\Leftrightarrow y=m-1\Leftrightarrow OB=\left|m-1\right|\end{matrix}\right.\\ \text{Kẻ }OH\perp\left(d\right)\Leftrightarrow\dfrac{1}{OH^2}=\dfrac{1}{OA^2}+\dfrac{1}{OB^2}=\dfrac{\left(m-4\right)^2}{\left(m-1\right)^2}+\dfrac{1}{\left(m-1\right)^2}\\ \text{Đặt }OH^2=t\Leftrightarrow\dfrac{1}{t}=\dfrac{m^2-8m+17}{m^2-2m+1}\\ \Leftrightarrow m^2t-8mt+17t=m^2-2m+1\\ \Leftrightarrow m^2\left(t-1\right)-2m\left(4t-1\right)+17t-1=0\\ \Leftrightarrow\Delta'=\left(4t-1\right)^2-\left(t-1\right)\left(17t-1\right)\ge0\\ \Leftrightarrow-t^2+10t\ge0\Leftrightarrow0\le t\le10\\ \Leftrightarrow OH_{max}=\sqrt{10}\Leftrightarrow\dfrac{m^2-2m+1}{m^2-8m+17}=10\Leftrightarrow...\)

Bình luận (0)
CM
Xem chi tiết
KY
3 tháng 8 2021 lúc 17:17

He asked me to know what the time was.

She asked me when we would meet again.

She asked him If he was crazy.

He asked me to know when they had lived.

He asked her If she would be at the party.

She asked me If I could meet her at the station.

The teacher asked me to know who knew the answer

She asked him to know why he didn't help her.

He asked me If I had seen that car.

The mother asked the twins If they had tidied up their room.

Tom asked how much that computer was

Bình luận (1)
LT
3 tháng 8 2021 lúc 17:18

11. what the time was.

12. when they would meet again.

13. if he was crazy.

14. where they had lived.

15. if she would be at the party.

16. if I could meet her at the station.

17. who knew the answer.

18. why I didn't help her.

19. if I had seen that car.

20. if they had tidied up their room.

Bài 3:

asked how much that computer was.

Bình luận (1)
TT
Xem chi tiết
EC
19 tháng 9 2021 lúc 12:48

Ta có: \(\left\{{}\begin{matrix}p+e+n=52\\p=e\\n-p=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}p=e=17\\n=18\end{matrix}\right.\)

Bình luận (0)
KN
Xem chi tiết
NL
6 tháng 1 2022 lúc 17:52

A là đáp án đúng

Bình luận (1)
LN
Xem chi tiết
AN
Xem chi tiết
H24
2 tháng 4 2022 lúc 8:42

Câu 2 :

a) PTHH : \(2Al+3S-->Al_2S_3\)

               \(Zn+S-->ZnS\)

mS = 29,55 - 15,15 = 14,4 (g)

b) nS = 14,4/32 = 0,45 (mol)

PTHH : \(Al_2S_3+3H_2SO_4-->Al_2\left(SO_4\right)_3+3H_2S\)

                \(ZnS+H_2SO_4-->ZnSO_4+H_2S\)

               \(H_2S+2AgNO_3-->Ag_2S+2HNO_3\)

Bảo toàn S : nAg2S = nH2S = nS = 0,45 (mol)

=> mktAg2S = 111,6 (g)

c) PTHH : \(H_2S+CuCl_2-->CuS+2HCl\)

nH2S = 0,45/2 = 0,225 (mol)

Theo pthh : nCuS = nH2S = 0,225 (mol)

=> mCuS = 0,225.96 = 21,6 (g)

Bình luận (0)
AN
Xem chi tiết
H24
25 tháng 3 2022 lúc 23:21

a)

Gọi số mol Fe, Al là a, b (mol)

=> 56a + 27b = 8,94 (1)

\(n_{H_2}=\dfrac{0,36}{2}=0,18\left(mol\right)\)

PTHH: Fe + 2HCl --> FeCl2 + H2

              a------------->a----->a

            2Al + 6HCl --> 2AlCl3 + 3H2

             b---------------->b------>1,5b

=> a + 1,5b = 0,18 (2)

(1)(2) => a = 0,15 (mol); b = 0,02 (mol)

=> \(\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{0,15.56}{8,94}.100\%=93,96\%\\\%m_{Al}=\dfrac{0,02.27}{8,94}.100\%=6,04\%\end{matrix}\right.\)

b) 

mFeCl2 = 0,15.127 = 19,05 (g)

mAlCl3 = 0,02.133,5 = 2,67 (g)

Bình luận (0)