What is a conjugate acid-base pair ? Write the conjugate acid and conjugate base of each of the following :
a) `OH^(-) " b) " HCO_(3)^(-)`

Explanation

An acid after losing a proton becomes a base where as a base after accepting the proton becomes an acid.
eg:
`underset("Acid"_(1))(H_(2)O(l))+underset("Base"_(2))(NH_(3)(aq))hArrunderset("Acid"_(2))(NH_(4)^(+)(aq)+underset("Base"_(1))(OH^(-))(a)`
A base formed by the loss of a proton by an acid is called conjugate base of the acid.
An acid formed by gain of a proton by the base is called conjugate acid of the acid.
Acid base pairs such as `H_(2)"O"//OH^(-)` and `NH_(4)^(+)//NH_(3)` which are formed by loss or gain of a proton are called conjugate acid base pair.
An acid base pair which differ by one proton is called conjugate acid base pair.
In the above examples `H_(2)"O"//OH^(-)` and `NH_(4)^(+)//NH_(3)` are conjugate acid base pairs.
A strong acid would have large tendency to donate proton. Thus conjugate base of a strong acid would be a weak base. SImilarly, conjugate base of a weak acid would be a strong base.