Nguyễn Hoàng Nhật Linh's Profile

cho 3 điện tích điểm q1= q2= q3= 5nC lần lượt đặt tại 3 điểm A,B,C trong chân không với AB=BC=10cm, AC=10cm. Xác định lực điện tổng hợp tác dụng lên q2 đặt tại B và lực điện tổng hợp tác dụng lên q3 tại C

 

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âu 1 : Nguyên tố R thuộc nhóm A, tạo được oxit cao nhất có công thức RO₃. Trong hợp chất khí với hiđro phần trăm khối lượng của R bằng 94,18%.  

a) Xác định nguyên tố R

b) Viết công thức phân tử và công thức cấu tạo của hiđroxit cao nhất của R.

c) Cho 3,0 gam hỗn hợp X (gồm Al và Mg) hòa tan hoàn toàn bằng dung dịch hiđroxit cao nhất của R trên,giải phóng 3,36 l khí H₂ ở đktc và dung dịch B. Cho B vào NaOH dư­, lấy kết tủa rửa sạch nung tới khối lượng không đổi thu được m gam chất rắn. Tính % khối lượng các chất trong X và giá trị của m?

1. (Lose) ………….my keys, I didn’t know how (get) ………in the house.
2. Last year I (make)……….. (clean) ………..the classroom for two weeks.
3. He (not have)……….. the accident if he (not drive) ………so fast.
4. John (water) ……….the flowers when it (start) ………….to rain.
5. When we (get) ……….to her house last week, she (just leave)………….
6. She (come)…………….. at 9 am. So, she (be) ……………here for more than 4 hours.
7. My parents would rather I (find)… a job, but I’d rather (go) ..to university for higher education.
8. Jane (do) the test again at the moment because she (not pass) ……………it the first time.
9. The man (sit)…………. next to me was nervous because he (not fly) …………before.
10. I (never forget)……….. what you (just tell) ……..me, I promise.

a, 2Fe + 6H2SO4 $\to$ Fe2(SO4)3 + 6H2O + 3SO2

Mg + 2H2SO4$\to$ MgSO4 + 2H2O + SO2

b,Bảo toàn electron ta có: $n_{SO2}=\frac{8,96}{22,4}=0,4\left(mol\right)$

$F{\mathrm{e0}}^{}\to F{\mathrm{e+3}}^{}+3e$${\mathrm{S+6}}^{}+2e\to {\mathrm{S+4}}^{}$

x (mol) 3x               0,8 0,4 (mol)

$M{\mathrm{g0}}^{}\to M{\mathrm{g+2}}^{}+2e$ 

y            2y (mol)

  ta có hpt:$\begin{array}{c}3x+2y=0,\mathrm{8;}\end{array}$ 56x+24y=13,6⇔x=0,2(mol),y=0,1(mol)

 => %mFe=82,35%

%mMg=17,65%

I …………………. this film twice.  (see)

The train ………………….when we got to the station. (just, leave)

It is raining now. It began raining two hours ago. So it …………………. for two hours. (rain)

As soon as Martina (see) ……………..  the fire, she ………….the fire department. (telephone)

Before Jennifer won the lottery, she …………. any kind of contest. (not, enter)

Every time Parkas sees a movie made in India, he ……………homesick. (feel)

The last time I ………………….in Athens, the weather was hot and humid. (be)

After the race …………………., the celebration began. (win)

At this time tomorrow, we …………………. our final exam. (take)

Peter said he ………………….a test the following day. (have)

I will tell Anna all the news when I ……………… her. (see)

Before the invention of the steamboat there ……………… no way to cross the ocean. (be)

He said that he ……………… his homework since 7 o’clock. (do)

She won't get married until she ………………25 years old. (be)

After Mary ……………… her degree, she intends to work in her father's company. (finish)

By the end of this month, I………………English for 6 years. (learn)

Up to now, I ……………… a lot of information about her.  (know)

This house ………………35,000 pounds in 1980. (cost)

I don’t remember where and when I………………her. (meet)

At this time yesterday I ……………… to music. (listen)

Bill (have) ………………breskfast when I stopped at this house.

It (rain………………heavily when I (sleep) ……………… yesterday afternoon.

He (do) …………… a lot of jobs before he (work)……………in this company.

After they (visit) ………………. Paris, they (go) ………………to Manchester.

Before I could say anything, they (admit) ……………… their mistakes.

I (hit) ……………… my thumb while I (use) ………………. the hammer. Ouch! That (hurt) ……

While I (read) ………………books in the living room last night, I (hear) ……………… a strange noise in the kitchen. I (go) ………………to the kitchen, (turn) ………………. on the lights. I (hold) ………………my break and (listen) ……………… carefully. I (realise) ……………… that a mouse (chew) ………………on something under the cupboard.

The vase broke when it (move) ……………… to the other room.

When I entered his room, I saw him (sleep) ……………… in a chair.

If only I (have) ……………… money with me, I (lend) ………………you some.

Why are you under the table?    You (look) ………………for something?

David (wash) ……………… his hands. He just (repair) ………………the TV set

The radio (play) ………………since 7 a.m. I wish someone would turn it off.

  Mr. Brown just (finish) ……………reading the letter when the telephone  on his desk ( ring) …

  Those students who ( fail) ……………… the exam are going to take another one held in August

  Hurry up or you (be) ……………… late for class.

  Hurry up or our favourite TV programme ( be) over long before we ( reach) home

  I (not have) ………………much time for entertainment these days.

  Two robbers (put) ………………in prison (escape) ………………yesterday.

  It is 2 years since I (last give) ………………presents on Christmas day.