\(n_{Fe_3O_4}=\dfrac{8}{232}=\dfrac{1}{29}\left(mol\right)\)

\(Fe_3O_4+8HCl\rightarrow FeCl_2+2FeCl_3+4H_2O\)

\(\dfrac{1}{29}.......\dfrac{8}{29}................\dfrac{2}{29}\)

\(m_{HCl}=\dfrac{8}{29}\cdot36.5=10.06\left(g\right)\)

\(m_{FeCl_3}=\dfrac{2}{29}\cdot162.5=11.21\left(g\right)\)

ờ...tớ ko nhầm thì thừa are

nếu bỏ are thì she's making a papper boat

Bỏ are, she's making a paper boat

có 2 từ She

a) \(\dfrac{3}{4}+\dfrac{9}{5}\div\dfrac{3}{2}-1=\dfrac{3}{4}+\dfrac{18}{15}-1=\dfrac{39}{20}-1=\dfrac{19}{20}\)

b) \(\dfrac{6}{7}\cdot\dfrac{8}{13}+\dfrac{6}{13}\cdot\dfrac{9}{7}-\dfrac{4}{13}\cdot\dfrac{6}{7}=\dfrac{48}{91}+\dfrac{54}{91}-\dfrac{24}{91}=\dfrac{48+51-24}{91}=\dfrac{78}{91}=\dfrac{6}{7}\)

c) \(\dfrac{-3}{7}+\left(\dfrac{3}{-7}-\dfrac{3}{-5}\right)\)\(=\dfrac{-3}{7}+\left(\dfrac{-3}{7}-\dfrac{-3}{5}\right)=\dfrac{-3}{7}+\dfrac{6}{35}=-\dfrac{9}{35}\)

a: Xét tứ giác AEHF có 

\(\widehat{AEH}=\widehat{AFH}=\widehat{FAE}=90^0\)

Do đó: AEHF là hình chữ nhật

1 How long do you live in HN

2 How often did you go to the movies

3 What did Mrs Robinson buy

4 When was your father in Nghe An

5 How do they go to school

6 Why didn't she go to class

7 Who left home at 7o'clock yesterday

8 What subject does he study in the high school

9 What is your favorite hobby

10 How far is it

3. are there any eggs?-No, there aren't some

4.is there any salt?- yes, there is any

5.are there any carrots?-yes, there are some

6.are there any apples?-no there aren't some

7.is there any suger?-yes, there is any

8.are there any cakes?-no there aren't some

9.is there any butter?-no. there isn't any

10. is there any mineral water?- yes. there is any

b: Gọi giao của AH với BC là F

=>AH vuông góc BC tại F

góic CHI=góc AHD=90 độ-góc HAD=góc ABC=1/2*sđ cung AC

góc CIH=1/2*sđ cung CA

=>góc CHI=góc CIH

=>ΔCHI cân tại C

c:

góc BDC=góc BEC=90 độ

=>BDEC nội tiếp đường tròn đường kính BC

=>MD=ME

=>ΔMDE cân tại M

mà MN là trung tuyến

nên MN vuông góc DE

Kẻ tiếp tuyến Ax của (O)

=>góc xAC=góc ABC

=>góc xAC=góc AED

=>Ax//DE

=>DE vuông góc OA

=>MN//AO

\(a, 48.19+81.48\)

\(=49.(19+81)\)

\(=49.100=4900\)

\(b,23.134-34.23\)

\(=23.(134-34)\)

\(=23.100=2300\)

e: =49-18-60=31-60=-29

a, 48.19+81.48
= 48.(19+81)
= 48.100
= 4800
b, 23.134 - 34.23
= 23.(134 - 34)
= 23.100
= 2300 
c,27.63+27.37
= 27.(63+37)
= 27.100
= 2700
d,64+125.147 - 47.125
= 64+125.(147 - 47)
= 64+125.100
= 64+12500
= 12564
e,(7² - 2.3²) - 60
= (49 - 2.9) - 60
= (49 - 18) - 60
=31 - 60
= 31+(-60)
= - (60 - 34)
= -29
f, 10² - 60:(5⁶:5⁴ - 3.5)
= 100 - 60:(5² - 3.5)
= 100 - 60:(25 - 3.5)
= 100 - 60:(25 - 15)
= 100 - 60:10
= 100 - 6
= 94
g, 3⁴.5²+122 - 2⁴.7 - 5²
= 81.25+122 - 16.7 - 25
= 2025+122 - 112 - 25
= 2147 - 112 - 25
= 2035 - 25
= 2010
h, 7⁴:7²+[6² - (10² - 4.16)]
= 7²+[36 - (100 - 4.16])
= 49+[36 - (100 - 4.16)]
= 49+[36 - (100 - 64)]
= 49+[36 - 36]
= 49+0
= 49
i, - 2015+145+( - 145)+15
= - 2015+[145+( - 145)]+15
= - 2015+0+15
= - 2015+15
= - ( 2015-15)
= - 2000
j, 25 - 18+( - 43)
= 7+ ( - 43)
= - (43 - 7)
= - 36
k, ( - 297) + 630 + 297 + ( - 330)
= [( - 297)+297]+630+( - 330)
= 0+630+( - 330)
= 630 - 330
= 300
l, ( - 25)+34+( - 75)+66
= [( - 25)+( - 75)]+(34+66)
= [ - (25+75)]+100
= ( - 100)+100
= 0
m, 568 - {5.[143 - (4 - 1)² ]+10}:10
= 568 - {5.[143 - 3² ]+10}:10
= 568 - {5.[143 - 9]+10}:10
= 568 - {5.134+10}:10
= 568 - {670+10}:10
= 568 - 680:10
= 568 - 68
= 500
n, 107 - {38+[7.3² - 24:6+(9 - 7)³ ]}:15
= 107 - {38+[7.9 - 24:6+(9 - 7)³ ]}:15
= 107 - {38+[7.9 - 24:6+2³ ]}:15
= 107 - {38+[7.9 - 24:6+8]}:15
= 107 - {38+[63 - 4+8]}:15
= 107 - {38+[59+8]}:15
= 107 - {38+67}:15
= 107 - 105:15
= 107 - 7
= 100

3 C
4 B

5 A

6 B

7 A
8 A

9 C

10 D

11 B

12 B

13 A

14 C

15 B

16 A

17 D

18 D

19 C

20 A

21 B

22 B

23 C

24 D

25 B

26 D

27 A

28 D

29 C

30 B

31 C

32 A

33 A

Viết lại câu

12 

Authorities in Ho Chi Minh City suggested that current school break schould be extended by us until the end of March to control the epidemic caused by Covid-19

15 The plumber who has just been had check the pipes in my house is very skillful

16 In spite of the fact that we had invited her to the party, she didn't come

17 Since they didn't have a map, they lost their way

18 I suggest that energy-saving bulbs should be used to reduce the electricity bill

19 We are looking forward to seeing your gook action from your company 

20 Linda congratulated Owen on scoring a wonderful goal

21 She had all the water pipes in her house checked by the plumber yesterday

22 If you go on smoking, you will be seriously sick

23 I suggested all the bag should be collected and taken to the garbage dump

24 If you aren't carefull, you will fall over the rocks

25 If you work too much, you will feel tired

26 If you are careless, you'll break the vase

27 Because of the fact that I am sick, I don't go out

28 Because of the fact that the water is polluted, we can't swim in that river

29 Because of the fact that Nga has had a sore leg, she had difficulty in walking

30 Because of having behaved badly, he found himself in trouble

31 Because he was seriously sick, he couldn't come to the class

32 Because of too much exhaust fume, people have to wear.........