1) al₂o₃→al₂(so₄)₃→al(oh)₃→al₂o₃ 2) fe₂(so₄)₃→fe(oh)₃→fe₂o₃→fe₂(so₄)₃ 3) p→p₂o₅→h₃po₄→ca₃(po₄)₂→h₃po₄→ca(h₂po₄)₂ 4) so₃→znso₄→zn(oh)₂→zno

1)Al2O3+3H2SO4=> Al2(SO4)3 + 3H2O

Al2(SO4)3+3Ba(OH)2=>
3BaSO4 + 2Al(OH)3

2Al(OH)3=>Al2O3+3H2O

2)Fe2(SO4)3+6KOH=>
3K2SO4+2Fe(OH)3

2Fe(OH)3=>Fe2O3+3H2O

Fe2O3+3H2SO4=>
Fe2(SO4)3 + 3H2O

3)4P+5O2=>2P2O5

P2O5+3H2O=>2H3PO4

2H3PO4+Ca(OH)2=>
Ca(H2PO4)2 + 2H2O