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Tổng số hạt trong M2X là 140, ta có:
\(\Rightarrow2\left[2P\left(M\right)+N\left(M\right)\right]+2P\left(X\right)+N\left(X\right)=140\)
\(\Leftrightarrow4P\left(M\right)+2P\left(X\right)+2N\left(M\right)+N\left(X\right)=140\) (1)
Số hạt mang điện nhiều hơn không mang điện là 44:
\(\Rightarrow4P\left(M\right)+2P\left(X\right)-\left[2N\left(M\right)+N\left(X\right)\right]=44\) (2)
Số khối của M{+} nhiều hơn X{2-} là 23:
\(\Rightarrow P\left(M\right)+N\left(M\right)-\left[P\left(X\right)+N\left(X\right)\right]=23\)
\(\Leftrightarrow P\left(M\right)-P\left(X\right)+N\left(M\right)-N\left(X\right)=23\) (3)
Tổng số hạt trong M{+} nhiều hơn trong X{2-} là 31:
\(\Rightarrow2P\left(M\right)+N\left(M\right)-1-\left[2P\left(X\right)+N\left(X\right)+2\right]=31\)
\(\Leftrightarrow2\left[P\left(M\right)-P\left(X\right)\right]+N\left(M\right)-N\left(X\right)=31\) (4)
Lấy (1) + (2) , ta có:
\(\Rightarrow8P\left(M\right)+4P\left(X\right)=184\) (5)
Lấy (4) - (3), ta có:
\(\Rightarrow P\left(M\right)-P\left(X\right)=11\) (6)
Từ 5; 6 \(\Rightarrow\orbr{\begin{cases}P\left(M\right)=9\\P\left(X\right)=8\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}M\text{ là }Kali\left(K\right)\\X\text{ là }Oxi\left(O\right)\end{cases}}\)
\(\Rightarrow M_2X\text{ là }K_2O\)
Số hạt mang điện trong hợp chất là (140+44)/2=92(hạt);
Số hạt mang điện trong M là (92-22)/2=35(hạt);
Số hạt mang điện trong X là (35+22)=57(hạt);
1. Đồi là núi già
2. Quốc kì = Énsign
3. Nga
4. 20 răng
5. Đấu vật
6 Than hoạt tính
7. 135 độ
8. NH3
9. Điểm uốn
10. Trọng lực
Mình không biết có đúng không. Nếu sai thì thông cảm cho mình, mình học dốt
1. The trains couldn’t run because of the snow.
=> The snow prevented the trains from running
2. I didn’t arrive in time to see her.
=> I wasn’t early enough to see her
3. I’m sorry I was rude to you yesterday.
=> I apologize for being rude to you yesterday
4. He didn’t hurry, so he missed the train.
=> If he had hurried, he wouldn't have missed the train
5. Janet is the best tennis- player in the club.
=> No one in the club plays tennis as well as Janet
6. I haven’t seen that man here before.
=> It’s the first time I have seen that man here
7. The furniture was so expensive that I didn’t buy it.
=> The furniture was too expensive for me to buy
8. The robbers made the bank manager hand over the money.
=> The bank manager was made to hand over the money by the robbers
9. He learned to drive when he was 18.
=> He has learned to drive since he was 18
10. She had never been unhappy before.
=> She was unhappier than she had been before
11. It was so late that nothing could be done.
=> It was too late for something to be done
12. I asked the hotel porter to wake me at 8 o’clock the following morning.
=> “Please wake me up at 8 o'clock next morning" I told the hotel porter
13. They’ll have to change the date of the meeting again.
=> The date will have to be changed again
14. The garage is going to repair the car for us next week.
=> We are going to have the garage repair the car next week
15. The bus takes longer than the train.
=> The train doesn't take as long as the bus
16. John has not had his hair cut for over six months.
=> It’s six months since John last had his hair cut
17. Maria says she’ll like to have been put in a high class.
=> Maria wishes she would have been put in a high class
18. Would you like me to finish the work tonight?
=> I’ll finish the work tonight if you like
19. You may get hungry on the train, so take some sandwiches.
=> In case you get hungry you’d better take some sandwiches.
20. My husband didn’t leave the car keys, so I couldn’t pick him up at the station.
=> If my husband had left the car leys, we could have picked him up at the station
ko ngờ trong tiếng anh nhiều ngữ pháp ghê
hok thuộc ko đc cô ạ
1. All of the homework (A) given by our teachers (B) are (C) useful to every (D) student.
B => is
2. When Helen (A) was a child, she (B) has worked in a factory (C) for (D) more than three years.
B => worked
3. The tourist guide only (A) has a (B) twenty-dollars bill with her (C) when she landed (D) at the airport.
B => twenty-dollar
4. After Mrs Wang (A) had returned (B) to her house (C) from work, she (D) was cooking dinner.
D => cooked
5. Elizabeth I (A) has reigned (B) as (C) Queen of England (D) from 1558 to 1603.
A => resigned
6. Caroline refused (A) taking the job (B) given to her (C) because the salary (D) was not good.
A => to take
7. I (A) finished college last year, and I (B) am working here for (C) only eight months (D) now.
B => have been working
8. If you think (A) carefully before (B) making your decision, you will avoid (C) to get into trouble (D) later.
C => getting
9. Each of the (A) members of the group (B) were made (C) to write a report every (D) week.
B => was
10. Last week Mark (A) told me that he (B) got very bored with his present job and (C) is looking for a (D) new one.
C => was looking
Mình chỉ giỏi tiếng anh thôi mấy cái này mình không rành