A 1.0g sample of pyrolusite ore containing `MnO_2` (MW = 87) was dissolved in a concentrated HCI solution and liberated `Cl_2` (g) was passed through a concentrated KI solution releasing `I_2` . If the liberated iodine required 16mL of 1.25 M sodium thiosulphate `(Na_(2)S_(2)O_3)` solution, mass percentage of `MnO_2` in the given sample is

Options

A. ` 43.5% `
B. `87%`
C. ` 21.75 %`
D. `0.875%`

Answer

B

Explanation

No.of eqts. `MnO_2` = No.of m.eqts .of `CI_2=` = No.of eqts .KI = No.of m.eqts. hypo No.of m.eqts of `MnO_(2)= 16x×1.25 = 16xx5/4=20`
No.of milli moles of `MnO_(2)=10`
Weight of `MnO_(2)=10` Weight % of `MnO_(2) =10xx87xx10^(-3)=0.87g`
Weight % of `MnO_(2)=(0.87)/1 xx100 =87%`