Câu 29: B
\(2Al^0+6H^{+1}Cl\rightarrow2Al^{+3}Cl_3+3H_2^0\)
Câu 27:
\(n_{hh}=\dfrac{6.72}{22.4}=0.3\left(mol\right)\)
\(n_{O_2}=a\left(mol\right)\)
\(n_{Cl_2}=b\left(mol\right)\)
\(n_{Mg}=0.1\left(mol\right)\)
\(n_{Al}=0.2\left(mol\right)\)
\(\text{Bảo toàn e : }\)
\(4a+2b=0.1\cdot2+0.2\cdot3=0.8\)
\(a+b=0.3\)
\(\Rightarrow a=0.1,b=0.2\)
\(V_{O_2}=0.1\cdot22.4=2.24\left(l\right)\)
Câu 30: Chọn A
\(HCl+NaOH\rightarrow H_2O+NaCl\)
\(n_{NaOH}=n_{HCl}=0,2.0,2=0,04\left(mol\right)\)
\(V_{ddNaOH}=\dfrac{0,04}{0,5}=0,08\left(l\right)=80\left(ml\right)\)
giúp mình với ạ ;-; . mình đang cần gấp lắm 
