One litre of an acidified solution of `KMnO_4` containing 15 g of `KMnO_4` is decolourised by passing sufficient amount of `SO_2`. If `SO_2`. If `SO_2` is produced by roasting of iron pyrites `(FeS_2)`. What will be the amount of pyrites required to produce the necessary amount of `SO_2`

Explanation

`underset(4xx120)(4FeSO_(2))+11O_(2)to2Fe_(2)O_(3)+underset(8xx64)(8SO_(2))`
Equivalents of `KMnO_(4)=(15.0)/(31.6)xx1` litre
`=0.5eq`
`=0.5" Eq of "SO_(2)`
`=0.5xx(64)/(2)g of SO_(2)`
`=16g of SO_(2)`
`8xx64g of SO_(2)` is produced from `2xx120g of FeS_(2)`
`therefore16 g of SO_(2)` is produced from `(4xx120)/(8xx64)xx16=15g`