chọn A

A nhé

Ta có \(n_{O_2}=\dfrac{V}{24,79}=\dfrac{4,958}{24,79}=0,2\left(mol\right)\)

\(\Rightarrow m_{O_2}=n.M=0,2.32=6,4\left(g\right)\)

=> Chọn A

a

\(SO_3+2NaOH\rightarrow Na_2SO_4+H_2O\\ n_{SO_3}=\dfrac{8}{40}=0,2\left(mol\right)\Rightarrow n_{Na_2SO_4}=n_{SO_3}=0,2\left(mol\right);n_{NaOH}=2.0,2=0,4\left(mol\right)\\ m_{NaOH}=0,4.40=16\left(g\right);m_{Na_2SO_4}=142.0,2=28,4\left(g\right)\)

các bạn giúp mình nha

\(n_{H_2SO_4}=0,6.1=0,6mol\\ n_{ZnO}=a;n_{Fe_2O_3}=b\\ a.ZnO+H_2SO_4\rightarrow ZnSO_4+H_2O\\ Fe_2O_3+3H_2SO_4\rightarrow Fe_2\left(SO_4\right)_3+3H_2O\\ b.\Rightarrow\left\{{}\begin{matrix}81a+160b=40,3\\a+3b=0,6\end{matrix}\right.\\ \Rightarrow a=0,3;b=0,1\\ \%m_{ZnO}=\dfrac{0,3.81}{40,3}\cdot100\%=60,3\%\\ \%m_{Fe_2O_3}=100\%-60,3\%=39,7\%\\ c.n_{ZnSO_4}=n_{Zn}=0,3mol\\ n_{Fe_2\left(SO_4\right)_3}=n_{Fe_2O_3}=0,1mol\\ C_{M_{ZnSO_4}}=\dfrac{0,3}{0,6}=0,5M\\ C_{M_{Fe_2\left(SO_4\right)_3}}=\dfrac{0,1}{0,6}M\)

\(a.n_{H_2}=\dfrac{6,72}{22,4}=0,3mol\\ n_{Mg}=a,n_{Na}=b\\ Mg+H_2SO_4\rightarrow MgSO_4+H_2\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ 2NaOH+H_2SO_4\rightarrow Na_2SO_4+H_2O\\ \Rightarrow\left\{{}\begin{matrix}24a+23b=9,4\\a+0,5b=0,3\end{matrix}\right.\\ \Rightarrow a=b=0,2\\ m_{Mg}=0,2.24=4,8g\\ m_{Na}=0,2.23=3,6g\\ b.n_{H_2SO_4}=0,5b+a=0,3mol\\ m_{ddH_2SO_4}=\dfrac{0,3.98}{10\%}\cdot100\%=294g\\ c.n_{MgSO_4}=n_{Mg}=0,2mol\\ n_{Na_2SO_4}=0,5n_{Na}=0,1mol\\ m_{MgSO_4}=120.0,2=24g\\ m_{Na_2SO_4}=142.0,1=14,2g\)

\(n_{CaCO_3}=\dfrac{50}{100}=0,5\left(mol\right)\\ a,PTHH:CaCO_3+2HCl\rightarrow CaCl_2+CO_2+H_2O\\ b,n_{CO_2}=n_{CaCl_2}=n_{CaCO_3}=0,5\left(mol\right)\\ V_{CO_2\left(25^oC,1bar\right)}=0,5.24,79=12,395\left(l\right)\\ c,n_{HCl}=2.0,5=1\left(mol\right)\\ V_{ddHCl}=\dfrac{1}{0,2}=5\left(l\right)\\ d,m_{CaCl_2}=111.0,5=55,5\left(g\right)\)