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

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

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

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

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

a: Xét tứ giác AEHF có 

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

Do đó: AEHF là hình chữ nhật

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

\(i=i'\)

\(\Rightarrow i'=30^o\)

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

Câu 15: B

SIMPLE PRESENT

1 Cars are produced in this factory.

2 Wheat is grown in the fields by the farmer.

3 The cows are milked by Mrs. Jones twice a day.

4 Wildlife photographs are taken by Mary every weekend.

Bị động hiện tại đơn: S+am/is/are+PII+(by O)+........

PRESENT CONTINUOUS

1 A new clinic is being built in the town.

2 Brownies are being baked by the children today.

3 Our homework is being done.

4 The car is being washed by the father.

Bị động thì hiện tại tiếp diễn: S+am/is/are+being + PII+( by O)+.........

PRESENT PERFECT

1 The book has already been discussed.

2 All the housework has been finished.

3 All their money has been lost.

4 His car has been crashed.

Bị động hiện tại hoàn thành: S+has/have+been+PII+(by O)+.......

PAST SIMPLE

1 The Harry Potter books were written by J K Rowling.

2 Their car was left in the garage.

3 All the washing was done yesterday.

4  Her wash was lost in the cinema

Bị động thì quá khứ đơn: S+was/were+PII+(by O)+.......

PAST CONTINOUS

1 The dishes were being washed when she arrived.

2  His homework was being done when the phone rang.

3 His car was being driven too fast.

4 The hall was being decorated for the party.

Bị động thì quá khứ tiếp diễn: S+ was/were+being + PII+(by O)+.....

PAST PERFECT

1 All his work had been finished before he left.

2 All the milk had been  delivered by the milkman by 6 o'clock.

3 The crime scene had been left by the thieves before the police arrived.

4 The door had already been locked before the burglars tried to enter.

Bị động thì quá khứ hoàn thành: S+ had been + PII+(by O)+.....

FUTURE SIMPLE

1 More workers will soon be hired by the company.

2 THe snake  will be killed if it comes any closer.

3 The lawn will be mown by my dad tomorrow.

4 The man will be bitten by the dog if the garden is come into by him.

Bị động thì tương lai đơn: S+will be+PII+(by O)+........

FUTURE-Be going to

1 All his  debt is going  to be paid

2 The murder is going to be investigated by the police.

3 The poachers are going to be shot on sight.

4  Several prisoners are going to be released.

Bị động thì tương lai gần: S+am/is/are+going to be+ PII+(by O)+......

MODAL

1 My car must be washed.

2  The children must be taught how to read by the teacher.

3 Her hair must be cut before the wedding.

4 The dog must be taken to the vet.

INFINITIVE

1 All the letters have to be delivered by the postman.

2 Our tickets have to be booked for the flight.

3  A new will has to be drawn up.

4 The light bulb has to be changed before it gets dark.

Bị động với V khuyết thiếu: S+V khuyết thiếu + be + PII+(by O)+......

\(Errink \times Cream\)

chiều rộng hình chữ nhật là:

54:(8-5)x5=90(m)

chiều dài hình chữ nhật là:

54+90=144(m)

chu vi hình chữ nhật là:

(144+900):2=522(m)

diện tích hình chữ nhật là:

144x900=129600(m²)

B

b

b