Entropy is a very important thermodynamic property. Change in entropy is positive in the following process

1.H2Og→H2Ol; ΔS=−ve2. 2Cs+H2g → C2H2g ;  ΔS = 03. Contraction of gas at const. T, volume ↓  ΔS = −ve4. 2KClO3s → 2KCls+3O2g;    ΔS = +ve