Làm nguội 280 g dung dịch NaNO₃ bão hòa từ 100^oC xuống 20^oC thì khối lượng dung dịch giảm : 180 - 88 = 92 ( g )

Ta có : 280g dung dich NaNO₃ từ 100^oC xuống 20^oC kết tinh 92 g

560 g dung dich NaNO₃ từ 100^oC xuống 20^oC kết tinh x g

\(\Rightarrow\)x = \(\dfrac{560\cdot92}{280}\)= 184 ( g )

Vậy khối lượng NaNO₃ kết tinh là 184 g

1. Our house is far from the school.

Our house is not near the school

2. What is the price of this pen?

How much does this pen cost ?

3. On the table are two cups of tea.

There are two cups of tea on the table .

4. Close your books, please!

Don’t open your books , please !

5. We have a lot of work to do.

There is a lot of work to do for us

6. How about going to the museum?.

Let’s go to the museum .

7. Does your school have four hundred students?

Are there four hundred students in your school ?

8. What is the width of the Great Wall ?

How wide is the Great Wall

9. Mr Hung usually drives to work.

Mr Hung usually goes to work by car

10. The Nile River is longer than the Red River.

The Red River is shorter than the Nile River .

d ) Gọi O là giao điểm của MB và AH

Ta có : MHNA là hình chữ nhật ( chứng inh ở câu b )

\(\Rightarrow\)OM = OA

\(\Rightarrow\) Tam giác OMA cân tại O

\(\Rightarrow\) \(\widehat{OMA}=\widehat{OAM}\)

Mà : \(\widehat{OAM}=\widehat{BCA}\)( cùng phụ với góc ABC )

\(\)\(\Rightarrow\widehat{OMA}=\widehat{BCA}\)

Hay : góc AMN = góc ACB