0.56 g of limestrone was treated with oxalic acid to give `CaC_(2)O_(4)`. The precipitate decolourised 50 " mL of " `(M)/(25)` `KMnO_(4)` in acidic medium. Calculate percentage of CaO in limestone.

Explanation

`underset("Limestone")(CaCO_(3))underset(acid)overset(oxalic)toCaC_(2)O_(4)overset(MnO_(4)^(ɵ))to` Decolourises
`m" Eq of "CaCO_(3)-=m" Eq of "CaC_(2)O_(4)-=m" Eq of "MnO_(4)^(ɵ)`
`m" Eq of "CaCO_(3)-=m" Eq of "CaO`
(Since CaO is present in `CaCO_(3))`
`m" Eq of "CaO-=m" Eq of "MnO_(4)^(ɵ)`
`(W)/((56)/(2))xx10^(3)-=50xx(1)/(25)xx5` (n factor)
`W_(CaO)=0.28g`
`% of CaO in lime stron e=(0.28xx100)/(0.56)=50%`