`50cm^(3)"of "0.04MK_(2)Cr_(2)O_(7)` in acidic medium oxidises a sample of `H_(2)S` gas to sulphur. Volume of `0.03M"HMn "O_(4)` required to oxidise the same amount of `H_(2)S` gas to sulphur in acidic medium is

Options

A. `60cm^(3)`
B. `80cm^(3)`
C. `90cm^(3)`
D. `120cm^(3)`

Answer

B

Explanation

`("Normality")/("Molarity")=("Molecular weight")/("Equivalent weight")`
`"For "K_(2)Cr_(2)O_(7),(N_(1))/(0.04)=(294)/(49)rArrN_(1)=0.24`
`"For "KMnO_(4),(N_(2))/(0.03)=(158)/(31.6)rArrN_(2)=0.15`
Now, from normality equation, `N_(1)V_(1)=N_(2)V_(2)`
`rArr0.24xx50=0.15xxV_(2),V_(2)=(0.24xx50)/(0.15)=80cm^(3)`