A 0.518 g sample of limestone is dissolved in HCl and then the calcium is precipitated as Ca_(2)C_(2)O_(4). After filtering and washing the precipitate, it requires 40 mL of 0.25 N KMnO_(4) solution acidified with H_(2)SO_(4) to titrate it as, MnO_(4)^(-) + H^(+) + C_(2)O_(4)^(2-) to CO_(2) + Mn^(2+) + 2H_(2)O The percentage of CaO in the sample is :

A 0.518 g sample of limestone is dissolved in HCl and then the calcium

1.	A 0.518 g sample of limestone is dissolved in HCl and then the calcium is precipitated as Ca_(2)C_(2)O_(4). After filtering and washing the precipitate, it requires 40 mL of 0.25 N KMnO_(4) solution acidified with H_(2)SO_(4) to titrate it as, MnO_(4)^(-) + H^(+) + C_(2)O_(4)^(2-) to CO_(2) + Mn^(2+) + 2H_(2)O The percentage of CaO in the sample is :
Answer» <html><body><p>0.54<br/>`27.1%`<br/>0.42<br/>0.84</p>Solution :Number of milliequivalents of `CaC_(2)O_(<a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a>), KMnO_(4) " and" <a href="https://interviewquestions.tuteehub.com/tag/cao-411869" style="font-weight:bold;" target="_blank" title="Click to know more about CAO">CAO</a>` will be same. <br/> `40xx0.25=(W)/(56//2)xx1000` <br/> W=0.28 g (<a href="https://interviewquestions.tuteehub.com/tag/mass-1088425" style="font-weight:bold;" target="_blank" title="Click to know more about MASS">MASS</a> of CaO) <br/> `% CaO=(0.28)/(0.518)xx100=54%`</body></html>