a) \(n_{MgCO_3}=\dfrac{33,6}{84}=0,4\left(mol\right)\)

PTHH: MgCO₃ + 2HNO₃ --> Mg(NO₃)₂ + CO₂ + H₂O

_______0,4---->0,8----------->0,4

\(C_{M\left(HNO_3\right)\left(C\right)}=\dfrac{0,8}{0,5}=1,6M\)

\(C_{M\left(Mg\left(NO_3\right)_2\right)\left(D\right)}=\dfrac{0,4}{0,5}=0,8M\)

b) Gọi \(\left\{{}\begin{matrix}C_{M\left(A\right)}=aM\\C_{M\left(B\right)}=bM\end{matrix}\right.\)

300ml dd A chứa: 0,3a mol HNO₃

200ml dd B chứa: 0,2b mol HNO₃

=> 0,3a + 0,2b = 0,8 (1)

200ml dd A chứa: 0,2a mol HNO₃

300ml dd B chứa: 0,3b mol HNO₃

=> \(\dfrac{0,2a+0,3b}{0,5}=1,4\) (2)

(1)(2) => a = 2 ; b = 1

Bài 8:

a: \(x^3+9x^2+27x+27=\left(x+3\right)^3\)

c: \(8-12x+6x^2-x^3=\left(2-x\right)^3\)

\(A=-2a^4bc^3\)-> bậc 8 

a) bên đường: trạng ngữ

cây cối : cái gì

xanh um: thế nào

a nhe

B.nhà cửa thưa thớt dần

a) Zn + 2HCl --> ZnCl₂ + H₂

Hiện tượng: Kẽm tan dần, sủi bọt khí

b)

\(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\); \(n_{HCl}=\dfrac{10,95}{36,5}=0,3\left(mol\right)\)

PTHH: Zn + 2HCl --> ZnCl₂ + H₂

Xét tỉ lệ: \(\dfrac{0,1}{1}< \dfrac{0,3}{2}\) => Zn hết, HCl dư

c)

PTHH: Zn + 2HCl --> ZnCl₂ + H₂

            0,1------------>0,1--->0,1

=> V_H2 = 0,1.22,4 = 2,24 (l)

m_ZnCl2 = 0,1.136 = 13,6 (g)

Đề bài 10 hình như chưa rõ ràng cho lắm

Bài 11:(Bài này mình không sure lắm!)

1. Jill is in London.

=> How long does Jill take to be in London?

2. I know Geogre.

=> How long have you known Geogre?

3.Mike and Judy are in Brazil.

=> How long do Mike and Judy take to be in Brazil?

4. Diana is learning Italian.

=> How long does Diana take to learn Italian.

5. My brother lives in Germany.

=> How long does your brother live in Germany?

6. It is rainning.

=> How long does it take from the rain stated to here?

7. Bill is a teacher.

=> How long does it take from the day Bil started teach to now?

8.  I know Margaret.

=> How long have you known Margaret?

9. I have a mortor bike.

=>How long do you have a mortor bike?

10. Linda and Frank are married.

=> How long have been when Linda and Frank?