100 ml aqueous 0.1 molar `M(CN)_(2)`, (80% ionized) solution is mixed with 100 ml of 0.05 molar `H_(2),SO_(2)` solution (80% ionized). `(K_(6)`, of CN" = `10^(-6)`)

Options

A. `6`
B. `8`
C. `9`
D. `7`

Answer

B

Explanation

`M(CN)_2 hArr M^(+2) + 2CN^(-) `
`10m " moles" `
` {:( 10(1- alpha ) , 10 alpha =8 , 2 xx 10 alpha = 16 ),( H_2SO_4 hArr, 2H^(+) , SO_4^(2-)),( 5 " moles" ,,),(5(1- beta ), 2 xx 5 beta =8, 5 beta =4 ), (H^(+) + , CN^(-) hArr, HCN),( 8,16,):}`
`8,8 `
i.e., buffer of HCN & `CN^(-) `
` therefore pH =pKa +log ""( S)/(A) =pKa =14 -6=8`