Answer : The correct option is, (C) 12.9
Explanation:
pOH : It is defined as the negative logarithm of hydroxide ion concentration.
Expression used :
[tex]pOH=-\log [OH^-][/tex]
First we have to calculate the pOH.
[tex]pOH=-\log [OH^-][/tex]
[tex]pOH=-\log (7.8\times 10^{-2})[/tex]
[tex]pOH=1.107[/tex]
Now we have to calculate the pH.
[tex]pH+pOH=14\\\\pH=14-pOH\\\\pH=14-1.107=12.9[/tex]
Therefore, the pH of a solution is 12.9
