Q.

The percentage of pyridine (C5H5N) that forms pyridinium ion (C5H5NH) in a 0.10 M aqueous pyridine solution (Kb for C5H5N=1.7×10-9) is                [2016]

1 0.0060%  
2 0.013%  
3 0.77%  
4 1.6%   

Ans.

(2)

C5H5N0.10 M+H2OC5H5N+H+OH-

α=KbC=1.7×10-90.10=1.30×10-4

  Percentage of pyridine that forms pyridinium ion=1.30×10-4×100=0.013%