\(\left(C_{6} H_{5}\right)_{3} \dot{C}>\left(C_{6} H_{5}\right)_{2} \dot{C} H>\left(C H_{3}\right)_{3} \dot{C}>\left(C H_{3}\right)_{2} \dot{C} H\)
The stabilisation of first two is due to resonance and last two is due to inductive effect.
$\mathop {C{H_3} - \mathop C\limits^ \oplus H - C{H_3}}\limits_I $
$\mathop {C{H_3} - \mathop C\limits^ \oplus H - OC{H_3}}\limits_{II} $
$\mathop {C{H_3} - \mathop C\limits^ \oplus H - C{H_2} - OC{H_3}}\limits_{III} $

