For the reaction $4Fe{S}_2+11O_2\to 2F{e}_2{O}_3+8S{O}_2$  . The equivalent mass of  $Fe{S}_2$ is M/X(M=Molecular mass  Of $Fe{S}_2$  ).Here the value of X=___

4FeS₂​+11O₂​⟶2Fe₂​O₃​+8SO₂​

1 mole of FeS₂​=11/4 moles of O₂​

Each O− atom takes 2e⁻ for reduction

∴1O₂​ molecule takes 4e⁻

∴ Number of e⁻ gained by O₂ ​= 11/4 ​× 4 = 11

∴ Number of e⁻ lost by FeS₂​=11

∴ Equivalent weight of FeS₂​ in this reaction= M​/11