In my opinion, Vietnamese teenagers should learn and practice. Among them, i think communication skill is one of the most important ones as this affects their future. Actually, many youngsters lacks of basic abilities of interact with people in the society. For example, they do not know how to have successful conversation with other people, especially the elder. In addition, they should boost their representation skill in public. In fact, Vietnamese students are quite shy and lack of confidence when speaking and giving their opinions in front of many others, which limits their creativity. Consequently, they cannot get good jobs after graduation although they graduate with flying colors.

oh my hat!

a, PTHH

4CO + Fe₃O₄ -> 4CO₂ + 3Fe (1)

4mol__1mol___________3mol

3H₂ + Fe₂O₃ -> 3H₂O + 2Fe (2)

3mol__1mol____________2mol

b. theo ptthh(1)ta có nH₂ = 0,2 .4 =0,8 (mol)

=>V_CO(đktc)= 0,8 . 22,4 =17,92 (lit)

theo pthh (2) nH₂= 0,2 . 3=0,6 (mol)

=>VH₂(đktc) = 0,6 . 22,4 =13,44(lit)

c,theo pthh (1) ta có nFe=3 nFe₃O₄= 3 . 0,2 =0,6 (mol)

=> mFe=0,6 . 56 =33,6 (gam)

theo pthh (2) ta có n^_Fe=2 nFe₃O₄=2 . 0,2 =0,4 (mol)

=> m_Fe = 0,2 . 56 =22,4 (gam)

Phản ứng hóa học điều chế H₂ trong phòng thí nghiêm là a và c

a. Zn + H₂SO₄ -> ZnSO₄ + H₂

c. 2Al + 6HCl-> 2AlCl₃ +H₂

a. PTHH :Fe + H₂SO₄ -> FeSO₄ +H₂

nFe = 22,4 : 56 = 0,4 (mol)

nH₂SO₄ = 24,5 : 98 = 0,25 (mol)

Ta có nFe > nH₂SO₄ (0,4>0,25) nên Fe dư

n_{Fe dư} = 0,4-0,25 = 0,15 (mol)

Vậy m_{Fe dư} = 0,15 . 56 = 8,4 (gam)

b, Theo PTHH ta có nH₂ = nH₂SO₄ =0,25 (mol)

=> VH_{2 thu được (đktc)} =0,25 . 22,4 =5,6(lit)