AP EAMCET Engineering 2018 Apr 24 Shift 1 Paper

The dissociation reaction for monobasic acid is as follows: The concentration of hydrogen ion can be calculated as:
pH=−log[H+]
5=−log[H+]
[H+]=10−5M
The dissociation constant is calculated as:
Ka=

[10−5][10−5]

[0.10]

=10−9
Now, the value of pKa is derived as:
pK a=−log[Ka]
=−log(10−9)
=9