`n_(ZnCl_2)=0,2.1=0,2(mol)`
`a,`
`2Na+2H_2O->2NaOH+H_2`
`0,2` `0,2`
`ZnCl_2+2NaOH->Zn(OH)_2+2NaCl`
`0,1` `0,2` `0,1`
`n_(Zn(OH)_2)=\frac{9,9}{99}=0,1(mol)`
`=>m_(Na)=0,2.23=4,6(g)`
`b,`
`2Na+2H_2O->2NaOH+H_2`
`0,4` `0,4`
`ZnCl_2+2NaOH->Zn(OH)_2+2NaCl`
`0,2` `0,4` `0,2`
`n_(Zn(OH)_2)=\frac{19,8}{99}=0,2(mol)`
`=>m_(Na)=0,4.23=9,2(g)`
`c`
`2Na+2H_2O->2NaOH+H_2`
`0,8` `0,8`
`ZnCl_2+2NaOH->Zn(OH)_2+2NaCl`
`0,2` `0,4` `0,2`
`Zn(OH)_2+2NaOH->Na_2ZnO_2+2H_2O`
`0,2` `0,4`
`=>m_(Na)=0,8.23=18,4(g)`
