Ch4--> hcho--> ch3cl--> c2h6--> c2h5oh--> ch3cho !

1)CH4 + 4O2 = CH2O + H2O + 2O3
CH2O+ H2 =CH3OH
CH3OH + O2 = HCHO
2)HCHO + H2 = CH3OH
2CH3OH + Cl2 = 2CH3Cl + H2O
3)2CH3Cl+2Na = C2H6+2NaCl
4)C2H6 + Cl = C2H5Cl +HCl
   C2H5Cl + NaOH = C2H5OH + NaCl
5) C2H5OH + CuO = CH2CHO + Cu + H2O