A 0.518 g sample of lime stone is dissolved in HCl and then the calcium is precipitated as CaC_2O_4 After filtering and washing the precipitate, it requires 40.0 mL of 0.250 N KMnO_4solution acidified with H_2SO_4to titrate it as, MnO_(4)^(-)+H^(+) +C_(2)O_(4)^(2-) rarr Mn^(2+)+CO_(2)+2H_(2)O The percentage of CaO in the sample is:

A 0.518 g sample of lime stone is dissolved in HCl and then the calciu

1.	A 0.518 g sample of lime stone is dissolved in HCl and then the calcium is precipitated as CaC_2O_4 After filtering and washing the precipitate, it requires 40.0 mL of 0.250 N KMnO_4solution acidified with H_2SO_4to titrate it as, MnO_(4)^(-)+H^(+) +C_(2)O_(4)^(2-) rarr Mn^(2+)+CO_(2)+2H_(2)O The percentage of CaO in the sample is:
Answer» ` 54.0% ` `27.1% ` ` 42%` ` 84% ` Solution :No of MILLI EQUIVALENTS of lime STONE = no of milli equivalents of `CaC_(2)O_4` = noof milli equivalents of`KMnO_4` `= 40xx0.25 =10` No of milli moles of lime = 5 `:.` weight of `CaO = 5 xx 56 xx 10^(-3) = 0.28g` percentage of `CaO= (0.28)/(0.518)xx100=54.05%`