Liquid ammonia ionises to a slight extent. Its self ionisation constant is `10^(-30) at - 50^(@) C ` , then the number of amide iona present per 1 cc of it at `-50^(@) ` C is

Options

A. `6xx 10 ^(12) `
B. ` 3xx10^(12) `
C. ` 6xx10 ^(5) `
D. ` 3xx10^(3) `

Answer

C

Explanation

` NH_3 hArr NH_2^(-) +H^(+) `
` K = [NH_2^(-) ][H^(+) ] = 10 ^(-30 ) `
` [NH_2 ^(-) ] =sqrt( 10^(-30)) = 10 ^(-15) `
`" Moles of " NH_2^(-) = 10 ^(-15) xx (1)/( 1000) = 10 ^(-18) `
` therefore "No . of" NH_2^(-) " ions " 10 ^(-18) xx 6 xx 10 ^(23) = 6 xx 10 ^(-5)`