Question

Among the given compounds, the increasing order of stability of conjugate base is :

• A. $D<C<B<A$
• B. $A<B<C<D$
• C. $A<D<B<C$
• D. $B<C<D<A$

Answer 1

The correct option is D $B<C<D<A$

After the loss of proton, conjugate bases formed are :


Since, on losing $H^{+}$, structure A and D become neutral, so they are more stable than B and C
Between B and C :
Negative charge on more electronegative atom (oxygen) is more stable, as in structure C than less electronegative atom (nitrogen) as in structure B.
So, C is more stable than B.
Between A and D :
More the electronegativity, more is the stability of conjugate base.
Since electronegativity of oxygen is more than that of nitrogen
So, A is more stable than D
Overall increasing order of stability of conjugate base :
$B<C<D<A$