1) CH4 = C + 2H2
2) 2C + Ca = CaC2
3) CaC2 + 2H2O = Ca(OH)2 + C2H2
4) C2H2 + H2 = CH2=CH2 + H2 = CH3-CH3
5) CH3-CH3 + Cl2 = CH3-CH2-Cl + HCl
