1.6 g of pyrolusite ore was treted with 50 " mL of " 1.0 N oxalic acid and some sulphuric acid. The oxalic acid left undecomposed was raised to 250 mL in a flask. 25 " mL of " this solution, when titrated with 0.1 N `KMnO_4` required 32 " mL of " this solution. Find out the percentage of pure `MnO_2` and also the percentage of available oxygen from `MnO_2`.

Options

A. `10.86%`
B. `5.43%`
C. `1.086%`
D. none of these

Answer

B

Explanation

`m" Eq of "KMnO_(4)-=m" Eq of "H_(2)C_(2)O_(4)]_("excess in "25 mL)`
`impliesexcess m" Eq of "H_(2)C_(2)O_(4)` in 25 mL
`=0.01xx30=0.30`
Excess m" Eq of "`H_(2)C_(2)O_(4)` in 250 mL`=3.0mL`
m" Eq of "`H_(2)C_(2)O_(4)` used `=5-3=2`
`m" Eq of "MnO_(2)=2`
`(Weight)/((87)/(2))xx1000=2impliesweight=0.087g`
`% MnO_(2)=(0.087)/(1.6)xx100=5.43%`