`3.92` g of ferrous ammonium sulphate crystals are dissolved in `100` mL of water, `20` mL of this solution requires `18` mL of `KMnO_(4)` during titration for complete oxidation. The weight of `KMnO_(4)` present in one litre of the solution is

Options

A. 3.51 g
B. 12.38 g
C. 34.76 g
D. 1.238 g

Answer

A

Explanation

Eq. wt of ferrous ammonium sulphate =392
`therefore ` Normality of salt solution
`= (3.92)/(392) xx (1)/(1000) xx 1000 = 0.1N`
20mL of 0.1N salt solution ` = 18 mL ` of `KMnO_(4)` solution
` therefore ` Normality of `KMnO_(4)` solution ` = (20 xx 0.1)/(18) = (1)/(9)`N
Eq.wt of `KMnO_(4) = 31.6`
`therefore ` Strength of `KMnO_(4) = 31.6 xx (1)/(9) = 3.51 g //L` approx.