Question

carbon form only covalent bonds

Answer 1

Yes because of the Van Der Waals Forces I guess

Answer 2

Carbon forms only covanlent bond because in this outermost cell their are 4 electron then it is very difficult to loss its 4 electrons and gain 4 electrons from other element.They required many more energy fo loss or gain electron.So,it is not possible to ionic bond.That's why they shared their electrons with other element and form its compound with covalent bond.

I may be help you