Question

Which one is incorrect regarding the representation of buffer index ?

• A. $\frac{\left[\text{Conjugate base}\right]}{\left[\text{Weak Acid}\right]}<0.1$
• B. $\frac{\left[\text{Conjugate acid}\right]}{\left[\text{Weak Base}\right]}<10$
• C. $\frac{\left[\text{Conjugate base}\right]}{\left[\text{Weak Acid}\right]}>0.1$
• D. None of the above

Answer 1

The correct option is A $\frac{\left[\text{Conjugate base}\right]}{\left[\text{Weak Acid}\right]}<0.1$

It is generally accepted that a solution has a useful buffer index provided:
$0.1<\frac{\left[\text{Conjugate base}\right]}{\left[\text{Weak Acid}\right]}or\frac{\left[\text{Conjugate acid}\right]}{\left[\text{Weak Base}\right]}<10$.
So , $\frac{\left[\text{Conjugate base}\right]}{\left[\text{Weak Acid}\right]}<0.1$ i.e. option (a) is the incorrect.