Which of the two: `O_(2)NCH_(2)CH_(2)O^(–)` or `CH_(3)CH_(2)O^(–)` is expected to be more stable and why ?

Explanation

is more stable than because `NO_(2)` groups has -I-effect and hence it tends to disperse the -ve charge on the O-atom. In contrast, `CH_(3)CH_(2)` has +I-effect. It, therefore, tends to intensify the -ve charge and hence destabilizes it.