[Aravind]

i knw that inductive effect is permanent and electromeric is temperorybut does not know which type the others are .Are resonance and hyperconjugation effects also permanent . My text gives no info about whether they are temperory and permanent. I am a student doing self study , hence i need to get clarified on this .please help

[discodermolide]

Have a look here:
http://en.wikipedia.org/wiki/Hyperconjugation

and here

http://en.wikipedia.org/wiki/Resonance_(chemistry)

I would say that they are permanent.

[Mitch]

Resonance is definitely a permanent effect. Benzene won't readily become less stable because it gave up resonance temporarily. Hyperconjugation is a bit trickier, I would imagine it could be permanent or temporary, as determined about how easy it is for the molecule to rotate out of a hyperconjugation configuration.