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1 tháng 10 2021

PTHH: 2NaOH + H2SO4 ---> Na2SO4 + 2H2O

Ta có: \(C_{\%_{NaOH}}=\dfrac{m_{NaOH}}{100}.100\%=20\%\)

=> mNaOH = 20(g)

=> nNaOH = \(\dfrac{20}{40}=0,5\left(mol\right)\)

Theo PT: \(n_{H_2SO_4}=\dfrac{1}{2}.n_{NaOH}=\dfrac{1}{2}.0,5=0,25\left(mol\right)\)

=> \(m_{H_2SO_4}=98.0,25=24,5\left(g\right)\)

1 tháng 10 2021

Có thể đề sai nhé

Muốn trung hoà 100g dd NaOH 20% cần bao nhiêu gam H2SO4?A.49g

B.98g

C.196g

D.198g

theo anh tối thiểu 2

27 tháng 8 2021

chỉ cần 1 mẫu thử là Ba(OH)2

5 tháng 8 2021

2 có cụm whether or not để chỉ ý hỏi phân vân

3 name after : đặt tên theo ...

4 earn a living : kiếm sống

5 ở đây nghề nghiệp dùng job thôi

6 a label ở đây là phiếu xác nhận

7 Most + N số nhiều là hấu hết 

8 leave for somewhere là rời đi để đến đâu

9 seem + to have lost : hành động lost đã xảy ra ở quá khứ và k nhớ tgian nên dùng thì hiện tại hoàn thành

10 điều ước ở hiện tại dùng were cho tất cả ngôi

11 a waste of time : sự lãng phí tgian

12 income là nguồn thi nhập

13 may + V0 mang hàm ý sự cho phép làm gì

14 câu hỏi đuôi vế đầu dùng has never thì vế sau chỉ cần dùng has

15 ở đây tình huống quyển sách thú vị là có căn cứ ở đằng trước nên chọn must để diễn tả sự khẳng định chắc chắn

16 while + Ving mà ở đây là dạng bị động nên dùng is being repaired

20 tháng 12 2021

Gọi thể tích NaOH cần dùng là V(l)

=> nNaOH = 0,5V (mol)

nHCl = 0,2.0,1=0,02(mol); nH2SO4 = 0,1.0,1=0,01(mol

PTHH: NaOH + HCl --> NaCl + H2O

_____0,02<---0,02

2NaOH + H2SO4 --> Na2SO4 + 2H2O

_0,02<---0,01

=> 0,5V = 0,04

=> V = 0,08 (l)

27 tháng 6 2021

TXĐ: `D=RR\\{π/2+kπ ; -π/4 +kπ}`

Mà `-π/2+k2π` và `π/2+k2π \in π/2 +kπ`

`=>` Không nằm trong TXĐ.

mn giúp em ạ, mn giải thích lý do vì sao chọn đáp án đấy giúp em với ạ, em cảm ơn1. Which word has the underlined part pronounced differently form that of the others?A. blackboard            B. plumber            C. garbage           D. volleyballA. ordered          B. controlled           C. destroyed          D. eruptedA. trust             B. funnel        C. lunar        D. abruptA. nature         B. natural           C. naturally         D. damage2. Mark the letter A,B,C or...
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mn giúp em ạ, mn giải thích lý do vì sao chọn đáp án đấy giúp em với ạ, em cảm ơn

1. Which word has the underlined part pronounced differently form that of the others?

A. blackboard            B. plumber            C. garbage           D. volleyball

A. ordered          B. controlled           C. destroyed          D. erupted

A. trust             B. funnel        C. lunar        D. abrupt

A. nature         B. natural           C. naturally         D. damage

2. Mark the letter A,B,C or D to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

A. bulb                B. plumber            C. profitable             D. label

A. amount           B. achieve            C. dynamite            D. deforestation

 

3. Find the word whose underlined part differs from the other three in pronunciation.

A. nuclear          B. disappear            C. clearly             D. instead

A. corresponded           B. congratulated           C. impressed         D. painted

1
24 tháng 5 2022

1. Which word has the underlined part pronounced differently form that of the others?

A. blackboard  /b/          B. plumber /âm câm/           C. garbage   /b/        D. volleyball   /b/ 

A. ordered  /d/        B. controlled  /d/         C. destroyed   /d/       D. erupted   /id/

A. trust  /ʌ/           B. funnel /ʌ/       C. lunar /uː/      D. abrupt  /ʌ/

A. nature  /eɪ/       B. natural /æ/          C. naturally /æ/         D. damage /æ/

2. Mark the letter A,B,C or D to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

A. bulb  /b/       B. plumber  /âm câm/          C. profitable  /b/           D. label /b/

A. amount  /ə/        B. achieve  /ə/          C. dynamite /ə/           D. deforestation /eɪ/

 

3. Find the word whose underlined part differs from the other three in pronunciation.

A. nuclear  /ɪə/        B. disappear   /ɪə/          C. clearly   /ɪə/           D. instead /e/

A. corresponded   /id/        B. congratulated    /id/       C. impressed   /t/   D. painted  /id/

24 tháng 5 2022

em cảm ơn ạ

Mọi người ơi giúp em chọn đáp án đúng kèm giải thích chi tiết lý do vì sao chọn giúp em với ạ! Em cảm ơn rất nhiều ạ.11. I'm grateful that you helped my brother do that work.A. Thank you for helping my brother do that work.B. Thank you about helping my brother do that work.C. Thank you because you helped me do that work.D. Thank you that you help my brother do that work12. I find it impossible not to worry about Lan.A. I can't help feeling worried about LanB. Ifeel...
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Mọi người ơi giúp em chọn đáp án đúng kèm giải thích chi tiết lý do vì sao chọn giúp em với ạ! Em cảm ơn rất nhiều ạ.

11. I'm grateful that you helped my brother do that work.
A. Thank you for helping my brother do that work.
B. Thank you about helping my brother do that work.
C. Thank you because you helped me do that work.
D. Thank you that you help my brother do that work
12. I find it impossible not to worry about Lan.
A. I can't help feeling worried about Lan
B. Ifeel worried about Lan, but I can't do anything to help
C.I can't do nothing to help Lan although I feel worried about her
D. I'm unable to worry about Lan
13. You'd better take a taxi; it was raining hard outside
A. You'd better take a taxi in case it was raining
B. She advised us to take a tad because it was raining outside
C. She gave us a lift because it was raining heavily
D. She didn't lend us any raincoats but a taxi
14. My brother and I go to that school
A. I went to that school and my brother, too
B. I went to that school and so my brother did
C. I went to that school and so did my brother
D. I went to that school and so my brother did, too
15. The meeting was put off because of pressure of time
A. There was not enough time to hold the meeting
B. People wanted to get away, so the meeting began early
C. The meeting was planned to start in a short time
D. The meeting lasted much longer than usual
16. When they arrived, the good seats were already taken
A. They didn't get good seats because they arrived too late
B. They arrived late enough to get good seats
C. They had to stand for the whole show
D. We couldn't get good seats although we arrived early
17. They would never have accepted his money if they had known his plans
A. They knew what he wanted to do, so they refused his money
B. They agreed with his wishes because they were glad to have his money
C. They didn't know his plans and never took money from him
D. They took the money be offered them without realizing
18. He could not afford to buy the car
A. He couldn't buy the car because it was too expensive
B. He bought the car because it was expensive
C. He bought the car though it was expensive
D. He had enough money but he didn't buy the car
19. Tam is not good at English and neither am I
A. Neither Tam nor I am good at English
B. Either Tam or I am good at English
C. I'm not as good at English as Tam is
D. Tam isn't good at English but I am
20. This is the first time I attend such an exciting holiday.
A. The first holiday I attended was exciting.
B. I had the first exciting holiday.
C. My attendance at the first holiday was exciting.
D. I have never attended such an exciting holiday before.

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