Correct Answer - 2
For the oxidation of `A^(n+)` as :
`A^(n+) rarr AO_(3)^(-)` n-factor `= 5-n`
`rArr` Gram equivalent of `A^(n+) = 2.68 xx 10^(3)(5-n)`
Now equating the above gram equivalent with gram equivalent of `KMnO_(4)` :
`2.68 xx 10^(-3) (5-n) = 16.1 xx 10^(-3) xx 5`
`rArr n = +2`