Answer :
Answer : The correct option is, (A) [tex]2.6\times 10^{-11}M[/tex], acidic
Explanation:
pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.
When the value of pH is less then 7 then the solution will be acidic.
When the value of pH is more then 7 then the solution will be basic.
When the value of pH is equal to 7 then the solution will be neutral.
First we have to calculate the pH.
[tex]pH=-\log [H^+][/tex]
[tex]pH=-\log (3.9\times 10^{-4})[/tex]
[tex]pH=3.41[/tex]
Now we have to calculate the pOH.
[tex]pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-3.41=10.59[/tex]
Now we have to calculate the [tex]OH^-[/tex] concentration.
[tex]pOH=-\log [OH^-][/tex]
[tex]10.59=-\log [OH^-][/tex]
[tex][OH^-]=2.6\times 10^{-11}M[/tex]
Therefore, the [tex]OH^-[/tex] concentration is, [tex]2.6\times 10^{-11}M[/tex]