Công thức hoá học dạng chung : P\(_x\)O\(_y\)

Theo quy tắc hoá trị : x.V = y . II

Tỉ lệ : x/y = II/V = 2/5

x = 2 thì y=5

Vậy CTHH của hợp chất là P\(_2\)O\(_5\)

PTK = 2. NTK\(_P\) + 5. NTK\(_O\)= 2.31+5.16= 142(đvC)

20B

21B

22A

23B

C

1.What do you usually on the weekend?

2. When are they going to visit Hue?

3. Tuan is tasllest in the our class

4.What is the weather like in the spring?

21.What do you like doing in your free time?

22. I like going fishing with my dad on the weekend.

A

25A

26C

27D

28D

29A

30A

31D

32C

33A

34D

35C

70,56 m\(^3\)

A