8A

9A

10A

11B

12B

13A

Em cần chi tiết à?

\(n_{CaCl_2}=0,15.0,5=0,075\left(mol\right)\\ n_{NaCl}=0,05.2=0,1\left(mol\right)\\ V_{ddsau}=0,15+0,05=0,2\left(l\right)\\ \left[Ca^{2+}\right]=\left[CaCl_2\right]=\dfrac{0,075}{0,2}=0,375\left(M\right)\\ \left[Na^+\right]=\left[NaCl\right]=\dfrac{0,1}{0,2}=0,5\left(M\right)\\ \left[Cl^-\right]=0,375.2+0,5=1,25\left(M\right)\)

8 disappointing

12 preservation

13 seriously

Bài 13:

a: ĐKXĐ: \(\left\{{}\begin{matrix}x\ge1\\x\ne3\end{matrix}\right.\)

b: Ta có: \(P=\dfrac{x-3}{\sqrt{x-1}-\sqrt{2}}\)

\(=\dfrac{\left(\sqrt{x-1}-\sqrt{2}\right)\left(\sqrt{x-1}+\sqrt{2}\right)}{\sqrt{x-1}-\sqrt{2}}\)

\(=\sqrt{x-1}+\sqrt{2}\)

c: Thay \(x=12-6\sqrt{2}\) vào P, ta được:

\(P=\sqrt{11-6\sqrt{2}}+\sqrt{2}=3-\sqrt{2}+\sqrt{2}=3\)

d: Ta có: \(\sqrt{x-1}\ge0\forall x\) thỏa mãn ĐKXĐ

\(\Leftrightarrow\sqrt{x-1}+\sqrt{2}\ge\sqrt{2}\forall x\) thỏa mãn ĐKXĐ

Dấu '=' xảy ra khi x=1

Câu 14 :

- Tổng số chất :7 (Cu,Fe,CuO,Mg,KOH,C,Na₂CO₃)

Câu 15 :

- Chất chỉ thể hiện tính oxi hóa:  H₂SO₄ đặc nóng, F₂,O₃

Câu 16 : Không còn chất rắn không tan sau phản ứng.

Câu 13 : 

\(n_{SO_2} = \dfrac{2,24}{22,4} = 0,1 = n_{NaOH} \to \text{Muối sinh ra là}\ NaHSO_3\\ NaOH +S O_2 \to NaHSO_3\\ n_{NaHSO_3} = n_{SO_2} = 0,1(mol)\\ \Rightarrow m_{NaHSO_3} = 0,1.104 = 10,4(gam)\)

Tách riêng bài ra e nhé!

Có làm mới có ăn

Những cái loại không làm mà đòi có ăn thì ăn đầu bùi, ăn cức

Thế cho nó dễ.

3 should have done

4 had been waiting

5 had been finished

6 should wear

7 would play - hadn't been offered

8 are pulled - are moved

9 is named

10 had been burnt - have forgot

11 is - is closed

12 will have had - will be

13 didn't enter - should have won

9 Although the girl works hard from morning till night, her step mother isn't happy

10 Rice is grown in tropical countries

11 The countryside is more peaceful than the city, but I prefer living in the city

12 A lot of Chung Cakes are made on Tet holiday

13 Although Little Pea works hard from morning till night, her mother isn't happy

14 An ordinary car goes more slowly than a sport car

15 An's sister performs better than him

16 Many fesstivals are held by the Thai every year

17 I enjoy hanging out with my best friends

18 If you don't hurry up, you will be late for the race

b) \(\sqrt{25a^2}+3a\) \(=5\left|a\right|+3a\)

Vì a > 0 => |a| = a

=> 5|a| + 3a = 5a + 3a = 8a

cái nịt