Question

why carbon cannot gain or loss electrons?​

Answer 1

Carbon cannot lose or gain 4 electrons.

Only it is not favorable for carbon to lose those 4 electrons from its valence shell. Try finding the ionization energy of carbon and this will give you a better idea of why it is more favorable to add bonds then to remove electrons.  

  If it were to gain or lose electrons-  

   It would require large amount of energy to remove four electrons and forming C4+ cation    with six protons in its nucleus holding on to just two electrons.

  It would be difficult for the nucleus with six protons to hold on to ten electrons,    that is four extra electrons forming an anion C4−

 

Hope this may help u and be the brainliest ..