A 0.518 g sample of lime stone is dissolved in $HCl$ and then the calcium is precipitated as ${\rm{Ca}}{{\rm{C}}_2}{{\rm{O}}_4}$. After filtering and washing the precipitate, it requires 40.0 mL of $0.250N{\rm{KMn}}{{\rm{O}}_4},$, solution acidified with ${{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}$ to titrate is as, ${\rm{MnO}}_4^ - + {{\rm{H}}^ + } + {{\rm{C}}_2}{\rm{O}}_4^{2 - } \to {\rm{M}}{{\rm{n}}^{2 + }} + {\rm{C}}{{\rm{O}}_2} + 2{{\rm{H}}_2}{\rm{O}}$. The percentage of ${\rm{CaO}}$ in the sample is :

JEE CHEMISTRY MCQ: SOME BASIC CONCEPTS OF CHEMISTRY

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A 0.518 g sample of lime stone is dissolved in

HCl

and then the calcium is precipitated as

\mathrm{Ca}{\mathrm{C}_2}{\mathrm{O}_4}

. After filtering and washing the precipitate, it requires 40.0 mL of

0.250N\mathrm{KMn}{\mathrm{O}_4},

, solution acidified with

{\mathrm{H}_2}\mathrm{S}{\mathrm{O}_4}

to titrate is as,

\mathrm{MnO}_4^ - + {\mathrm{H}^ + } + {\mathrm{C}_2}\mathrm{O}_4^{2 - } \to \mathrm{M}{\mathrm{n}^{2 + }} + \mathrm{C}{\mathrm{O}_2} + 2{\mathrm{H}_2}\mathrm{O}

. The percentage of

\mathrm{CaO}

in the sample is :

View answer and explanation

Correct option: A

54.0\mathrm{ }\%

Option A (

54.0\%

) is correct because the percentage of CaO is calculated by equating the meq of limestone, CaC2O4, KMnO4 and CaO.