K_ a values for acids H ₂ SO ₃, HNO ₂, CH ₃ COOH and HCN are respectively 1.3 10⁻² , 4 10⁻⁴, 1.8 10⁻⁵ and 4 10⁻¹⁰ , which of the above acids produces stronger conjugate base in aqueous solution?

Step-by-step solution

Lower the value of K_ a , lower will be the acidic strength and stronger will be the conjugate base. Therefore, among the given acids, HCN has the lowest K_ a value (i.e. 4 10⁻¹⁰ ). Hence, it is the strongest conjugate base.