@IvanNeretin Thanks! I had read that 3d orbitals of $CCl_3^-$ stabilize it quite a bit so thought the same would apply here.

@IvanNeretin would the vacant 3d-orbitals of Sulphur not delocalize the negative charge? I understand that the extent of delocalization would be less and it won't change the answer yet no mention of it is making me confused.

@Mithoron True. I just used to think that the stabilizing effect of resonance is multitudes greater than negative charge on an sp Carbon.

@user55119 Then what do we mean when we say, "more substituted alkenes are more stable"? I have seen this statement in a lot of places.

@user55119 The one that has less positive heat of formation. I think of the measure of what reacts less rapidly with a particular electrophile as their reactivity.

@user55119 The more stable compound would start to disintegrate at a higher temperature.

@TeslaBolt I meant that propene has higher nucleophilicity than ethene. I am reacting them both with the same electrophile.

@KarstenTheis Thanks! How to compare between I and II?

Thank you. Wouldn't it increase nucleophilicity as well as electrophilicity of napthlene? The electrophiles can react with bonds with more bond order and nucleophiles can react with bonds with less bond order.